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C File Handling

A file is a container in computer storage devices used for storing data.

Why files are needed?

  • When a program is terminated, the entire data is lost. Storing in a file will preserve your data even if the program terminates.
  • If you have to enter a large number of data, it will take a lot of time to enter them all. However, if you have a file containing all the data, you can easily access the contents of the file using a few commands in C.
  • You can easily move your data from one computer to another without any changes.

Types of Files

When dealing with files, there are two types of files you should know about:

  • Binary files

1. Text files

Text files are the normal .txt files. You can easily create text files using any simple text editors such as Notepad.

When you open those files, you'll see all the contents within the file as plain text. You can easily edit or delete the contents.

They take minimum effort to maintain, are easily readable, and provide the least security and takes bigger storage space.

2. Binary files

Binary files are mostly the .bin files in your computer.

Instead of storing data in plain text, they store it in the binary form (0's and 1's).

They can hold a higher amount of data, are not readable easily, and provides better security than text files.

File Operations

In C, you can perform four major operations on files, either text or binary:

  • Creating a new file
  • Opening an existing file
  • Closing a file
  • Reading from and writing information to a file

Working with files

When working with files, you need to declare a pointer of type file. This declaration is needed for communication between the file and the program.

Opening a file - for creation and edit

Opening a file is performed using the fopen() function defined in the stdio.h header file.

The syntax for opening a file in standard I/O is:

For example,

  • Let's suppose the file newprogram.txt doesn't exist in the location E:\cprogram . The first function creates a new file named newprogram.txt and opens it for writing as per the mode 'w' . The writing mode allows you to create and edit (overwrite) the contents of the file.
  • Now let's suppose the second binary file oldprogram.bin exists in the location E:\cprogram . The second function opens the existing file for reading in binary mode 'rb' . The reading mode only allows you to read the file, you cannot write into the file.

Closing a File

The file (both text and binary) should be closed after reading/writing.

Closing a file is performed using the fclose() function.

Here, fptr is a file pointer associated with the file to be closed.

Reading and writing to a text file

For reading and writing to a text file, we use the functions fprintf() and fscanf().

They are just the file versions of printf() and scanf() . The only difference is that fprintf() and fscanf() expects a pointer to the structure FILE.

Example 1: Write to a text file

This program takes a number from the user and stores in the file program.txt .

After you compile and run this program, you can see a text file program.txt created in C drive of your computer. When you open the file, you can see the integer you entered.

Example 2: Read from a text file

This program reads the integer present in the program.txt file and prints it onto the screen.

If you successfully created the file from Example 1 , running this program will get you the integer you entered.

Other functions like fgetchar() , fputc() etc. can be used in a similar way.

Reading and writing to a binary file

Functions fread() and fwrite() are used for reading from and writing to a file on the disk respectively in case of binary files.

Writing to a binary file

To write into a binary file, you need to use the fwrite() function. The functions take four arguments:

  • address of data to be written in the disk
  • size of data to be written in the disk
  • number of such type of data
  • pointer to the file where you want to write.

Example 3: Write to a binary file using fwrite()

In this program, we create a new file program.bin in the C drive.

We declare a structure threeNum with three numbers - n1, n2 and n3 , and define it in the main function as num.

Now, inside the for loop, we store the value into the file using fwrite() .

The first parameter takes the address of num and the second parameter takes the size of the structure threeNum .

Since we're only inserting one instance of num , the third parameter is 1 . And, the last parameter *fptr points to the file we're storing the data.

Finally, we close the file.

Reading from a binary file

Function fread() also take 4 arguments similar to the fwrite() function as above.

Example 4: Read from a binary file using fread()

In this program, you read the same file program.bin and loop through the records one by one.

In simple terms, you read one threeNum record of threeNum size from the file pointed by *fptr into the structure num .

You'll get the same records you inserted in Example 3 .

Getting data using fseek()

If you have many records inside a file and need to access a record at a specific position, you need to loop through all the records before it to get the record.

This will waste a lot of memory and operation time. An easier way to get to the required data can be achieved using fseek() .

As the name suggests, fseek() seeks the cursor to the given record in the file.

Syntax of fseek()

The first parameter stream is the pointer to the file. The second parameter is the position of the record to be found, and the third parameter specifies the location where the offset starts.

Example 5: fseek()

This program will start reading the records from the file program.bin in the reverse order (last to first) and prints it.

Table of Contents

  • Types of files
  • Opening a file
  • Example: Write to a text file
  • Example: Read from a text file
  • Read and write binary files
  • Get data using fseek()

Sorry about that.

Related Tutorials

C Standard Library Functions

C Dynamic Memory Allocation

File Handling in C — How to Open, Close, and Write to Files

If you’ve written the C helloworld program before, you already know basic file I/O in C:

File handling is one of the most important parts of programming. In C, we use a structure pointer of a file type to declare a file:

C provides a number of build-in function to perform basic file operations:

  • fopen() - create a new file or open a existing file
  • fclose() - close a file
  • getc() - reads a character from a file
  • putc() - writes a character to a file
  • fscanf() - reads a set of data from a file
  • fprintf() - writes a set of data to a file
  • getw() - reads a integer from a file
  • putw() - writes a integer to a file
  • fseek() - set the position to desire point
  • ftell() - gives current position in the file
  • rewind() - set the position to the beginning point

Opening a file

The fopen() function is used to create a file or open an existing file:

There are many modes for opening a file:

  • r - open a file in read mode
  • w - opens or create a text file in write mode
  • a - opens a file in append mode
  • r+ - opens a file in both read and write mode
  • a+ - opens a file in both read and write mode
  • w+ - opens a file in both read and write mode

Here’s an example of reading data from a file and writing to it:

Now you might be thinking, "This just prints text to the screen. How is this file IO?”

The answer isn’t obvious at first, and needs some understanding about the UNIX system. In a UNIX system, everything is treated as a file, meaning you can read from and write to it.

This means that your printer can be abstracted as a file since all you do with a printer is write with it. It is also useful to think of these files as streams, since as you’ll see later, you can redirect them with the shell.

So how does this relate to helloworld and file IO?

When you call printf , you are really just writing to a special file called stdout , short for standard output . stdout represents the standard output as decided by your shell, which is usually the terminal. This explains why it printed to your screen.

There are two other streams (i.e. files) that are available to you with effort, stdin and stderr . stdin represents the standard input , which your shell usually attaches to the keyboard. stderr represents the standard error output, which your shell usually attaches to the terminal.

Rudimentary File IO, or How I Learned to Lay Pipes

Enough theory, let’s get down to business by writing some code! The easiest way to write to a file is to redirect the output stream using the output redirect tool, > .

If you want to append, you can use >> :

The contents of hello.txt will, not surprisingly, be

Say we have another program called greet , similar to helloworld , that greets you with a given name :

Instead of reading from the keyboard, we can redirect stdin to read from a file using the < tool:

Note: these redirection operators are in bash and similar shells.

The Real Deal

The above methods only worked for the most basic of cases. If you wanted to do bigger and better things, you will probably want to work with files from within C instead of through the shell.

To accomplish this, you will use a function called fopen . This function takes two string parameters, the first being the file name and the second being the mode.

The mode are basically permissions, so r for read, w for write, a for append. You can also combine them, so rw would mean you could read and write to the file. There are more modes, but these are the most commonly used.

After you have a FILE pointer, you can use basically the same IO commands you would’ve used, except that you have to prefix them with f and the first argument will be the file pointer. For example, printf ’s file version is fprintf .

Here’s a program called greetings that reads a from a file containing a list of names and write the greetings to another file:

Suppose names.txt contains the following:

Then after running greetings the file greet.txt will contain:

If this article was helpful, share it .

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How to Write to File in C?

C – write to file.

When a programs output or some of the variables has to be saved to a storage location on file system, the data has to be written to a file. In this tutorial, we shall learn how to write data to a file using some of the builtin functions of C programming language.

The following functions are used to write data into the file. They are:

The fprintf() is used to write formatted output to stream.It is used to write a set of characters into a file.

The syntax of fprintf() function is

stream ? This is the pointer to a FILE object that identifies the stream.

format ? This is the C string that contains the text to be written to the stream. It can optionally contain format tags,that are replaced by the values specified in subsequent additional arguments.prototype of format flag is: %[flags][width][.precision][length]specifier.

  • Flags which specifies the output justification such as decimal point,trailing 0’s,octal,hexadecimal prefixes.(-,+,#,0).
  • Width specifies the minimum number of characters to print after being padded with 0’s or blank spaces.
  • Precision specifies maximum number of characters to print.
  • Length defines whether the argument ia a short,long or double long.
  • Specifier is used to define the type and the interpretation of the value of the corresponding argument.

fputs() is used to write a line to a file.

The syntax of fputs() function is

The fputs() writes the string pointed to by str to the stream pointed to by stream.On successful completion ,it returns 0 else EOF.

fputc() is used to write a character to the stream.

The syntax of fputc() function is

The fgetc() function will write byte specified by c to the output stream pointed to by stream . On successful completion, fputc() will return the value it has written, else EOF  character will be returned.

The fwrite() function is used to write data (can contain multiple characters and multiple lines) to a file.

  • The fwrite() function will write objects of objects specified by size from an array pointed to by ptr to the stream pointed to by stream .
  • On successful completion,the fwrite() function returns the number of objects successfully written else EOF will be set.

In the following example, we will writing a variable to a file.

In this example, we will write an array to a file. The below code snippet writes an integer array to a file.

In this example, we will write structure to a file. To write a C structure to a file, use fwrite().

In this example, we will write char array to a file.

In this C Tutorial , we have learnt how to write variables or char array or stream of data into a file using different function available in C programming with examples.

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C Files I/O: Create, Open, Read, Write and Close a File

Barbara Thompson

C File management

A File can be used to store a large volume of persistent data. Like many other languages ‘C’ provides following file management functions,

  • Creation of a file
  • Opening a file
  • Reading a file
  • Writing to a file
  • Closing a file

Following are the most important file management functions available in ‘C,’

How to Create a File

Whenever you want to work with a file, the first step is to create a file. A file is nothing but space in a memory where data is stored.

To create a file in a ‘C’ program following syntax is used,

In the above syntax, the file is a data structure which is defined in the standard library.

fopen is a standard function which is used to open a file.

  • If the file is not present on the system, then it is created and then opened.
  • If a file is already present on the system, then it is directly opened using this function .

fp is a file pointer which points to the type file.

Whenever you open or create a file, you have to specify what you are going to do with the file. A file in ‘C’ programming can be created or opened for reading/writing purposes. A mode is used to specify whether you want to open a file for any of the below-given purposes. Following are the different types of modes in ‘C’ programming which can be used while working with a file.

In the given syntax, the filename and the mode are specified as strings hence they must always be enclosed within double quotes.

File is created in the same folder where you have saved your code.

How to Create a File

You can specify the path where you want to create your file

How to Create a File

How to Close a file

One should always close a file whenever the operations on file are over. It means the contents and links to the file are terminated. This prevents accidental damage to the file.

‘C’ provides the fclose function to perform file closing operation. The syntax of fclose is as follows,

The fclose function takes a file pointer as an argument. The file associated with the file pointer is then closed with the help of fclose function. It returns 0 if close was successful and EOF (end of file) if there is an error has occurred while file closing.

After closing the file, the same file pointer can also be used with other files.

In ‘C’ programming, files are automatically close when the program is terminated. Closing a file manually by writing fclose function is a good programming practice.

Writing to a File

In C, when you write to a file, newline characters ‘\n’ must be explicitly added.

The stdio library offers the necessary functions to write to a file:

  • fputc(char, file_pointer) : It writes a character to the file pointed to by file_pointer.
  • fputs(str, file_pointer) : It writes a string to the file pointed to by file_pointer.
  • fprintf(file_pointer, str, variable_lists) : It prints a string to the file pointed to by file_pointer. The string can optionally include format specifiers and a list of variables variable_lists.

The program below shows how to perform writing to a file:

fputc() Function:

Writing to a File

The above program writes a single character into the fputc_test.txt file until it reaches the next line symbol “\n” which indicates that the sentence was successfully written. The process is to take each character of the array and write it into the file.

Writing to a File

  • In the above program, we have created and opened a file called fputc_test.txt in a write mode and declare our string which will be written into the file.
  • We do a character by character write operation using for loop and put each character in our file until the “\n” character is encountered then the file is closed using the fclose function.

fputs () Function:

Writing to a File

  • In the above program, we have created and opened a file called fputs_test.txt in a write mode.
  • After we do a write operation using fputs() function by writing three different strings
  • Then the file is closed using the fclose function.

fprintf()Function:

Writing to a File

  • In the above program we have created and opened a file called fprintf_test.txt in a write mode.
  • After a write operation is performed using fprintf() function by writing a string, then the file is closed using the fclose function.

Reading data from a File

There are three different functions dedicated to reading data from a file

  • fgetc(file_pointer): It returns the next character from the file pointed to by the file pointer. When the end of the file has been reached, the EOF is sent back.
  • fgets(buffer, n, file_pointer): It reads n-1 characters from the file and stores the string in a buffer in which the NULL character ‘\0’ is appended as the last character.
  • fscanf(file_pointer, conversion_specifiers, variable_adresses) : It is used to parse and analyze data. It reads characters from the file and assigns the input to a list of variable pointers variable_adresses using conversion specifiers. Keep in mind that as with scanf, fscanf stops reading a string when space or newline is encountered.

The following program demonstrates reading from fputs_test.txt file using fgets(),fscanf() and fgetc () functions respectively :

Reading data from a File

  • In the above program, we have opened the file called “fprintf_test.txt” which was previously written using fprintf() function, and it contains “Learning C with Guru99” string. We read it using the fgets() function which reads line by line where the buffer size must be enough to handle the entire line.
  • We reopen the file to reset the pointer file to point at the beginning of the file. Create various strings variables to handle each word separately. Print the variables to see their contents. The fscanf() is mainly used to extract and parse data from a file.
  • Reopen the file to reset the pointer file to point at the beginning of the file. Read data and print it from the file character by character using getc() function until the EOF statement is encountered
  • After performing a reading operation file using different variants, we again closed the file using the fclose function.

Interactive File Read and Write with getc and putc

These are the simplest file operations. Getc stands for get character, and putc stands for put character. These two functions are used to handle only a single character at a time.

Following program demonstrates the file handling functions in ‘C’ programming:

Interactive File Read and Write with getc and putc

  • In the above program we have created and opened a file called demo in a write mode.
  • After a write operation is performed, then the file is closed using the fclose function.
  • We have again opened a file which now contains data in a reading mode. A while loop will execute until the eof is found. Once the end of file is found the operation will be terminated and data will be displayed using printf function.
  • After performing a reading operation file is again closed using the fclose function.
  • A file is a space in a memory where data is stored.
  • ‘C’ programming provides various functions to deal with a file.
  • A mechanism of manipulating with the files is called as file management.
  • A file must be opened before performing operations on it.
  • A file can be opened in a read, write or an append mode.
  • Getc and putc functions are used to read and write a single character.
  • The function fscanf() permits to read and parse data from a file
  • We can read (using the getc function) an entire file by looping to cover all the file until the EOF is encountered
  • We can write to a file after creating its name, by using the function fprintf() and it must have the newline character at the end of the string text.
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The last chapter explained the standard input and output devices handled by C programming language. This chapter cover how C programmers can create, open, close text or binary files for their data storage.

A file represents a sequence of bytes, regardless of it being a text file or a binary file. C programming language provides access on high level functions as well as low level (OS level) calls to handle file on your storage devices. This chapter will take you through the important calls for file management.

Opening Files

You can use the fopen( ) function to create a new file or to open an existing file. This call will initialize an object of the type FILE , which contains all the information necessary to control the stream. The prototype of this function call is as follows −

Here, filename is a string literal, which you will use to name your file, and access mode can have one of the following values −

If you are going to handle binary files, then you will use following access modes instead of the above mentioned ones −

Closing a File

To close a file, use the fclose( ) function. The prototype of this function is −

The fclose(-) function returns zero on success, or EOF if there is an error in closing the file. This function actually flushes any data still pending in the buffer to the file, closes the file, and releases any memory used for the file. The EOF is a constant defined in the header file stdio.h .

There are various functions provided by C standard library to read and write a file, character by character, or in the form of a fixed length string.

Writing a File

Following is the simplest function to write individual characters to a stream −

The function fputc() writes the character value of the argument c to the output stream referenced by fp. It returns the written character written on success otherwise EOF if there is an error. You can use the following functions to write a null-terminated string to a stream −

The function fputs() writes the string s to the output stream referenced by fp. It returns a non-negative value on success, otherwise EOF is returned in case of any error. You can use int fprintf(FILE *fp,const char *format, ...) function as well to write a string into a file. Try the following example.

Make sure you have /tmp directory available. If it is not, then before proceeding, you must create this directory on your machine.

When the above code is compiled and executed, it creates a new file test.txt in /tmp directory and writes two lines using two different functions. Let us read this file in the next section.

Reading a File

Given below is the simplest function to read a single character from a file −

The fgetc() function reads a character from the input file referenced by fp. The return value is the character read, or in case of any error, it returns EOF . The following function allows to read a string from a stream −

The functions fgets() reads up to n-1 characters from the input stream referenced by fp. It copies the read string into the buffer buf , appending a null character to terminate the string.

If this function encounters a newline character '\n' or the end of the file EOF before they have read the maximum number of characters, then it returns only the characters read up to that point including the new line character. You can also use int fscanf(FILE *fp, const char *format, ...) function to read strings from a file, but it stops reading after encountering the first space character.

When the above code is compiled and executed, it reads the file created in the previous section and produces the following result −

Let's see a little more in detail about what happened here. First, fscanf() read just This because after that, it encountered a space, second call is for fgets() which reads the remaining line till it encountered end of line. Finally, the last call fgets() reads the second line completely.

Binary I/O Functions

There are two functions, that can be used for binary input and output −

Both of these functions should be used to read or write blocks of memories - usually arrays or structures.

C Functions

C structures, file handling.

In C, you can create, open, read, and write to files by declaring a pointer of type FILE , and use the fopen() function:

FILE is basically a data type, and we need to create a pointer variable to work with it ( fptr ). For now, this line is not important. It's just something you need when working with files.

To actually open a file, use the fopen() function, which takes two parameters:

Create a File

To create a file, you can use the w mode inside the fopen() function.

The w mode is used to write to a file. However , if the file does not exist, it will create one for you:

Note: The file is created in the same directory as your other C files, if nothing else is specified.

On our computer, it looks like this:

write at file c

Tip: If you want to create the file in a specific folder, just provide an absolute path:

Closing the file

Did you notice the fclose() function in our example above?

This will close the file when we are done with it.

It is considered as good practice, because it makes sure that:

  • Changes are saved properly
  • Other programs can use the file (if you want)
  • Clean up unnecessary memory space

In the next chapters, you will learn how to write content to a file and read from it.

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File Input and Output in C

In order to read information from a file, or to write information to a file, your program must take the following actions. 1) Create a variable to represent the file. 2) Open the file and store this "file" with the file variable. 3) Use the fprintf or fscanf functions to write/read from the file.

File I/O in C

File I/O in C is very similar to Matlab. There are two main differences. One, we have to type the FILE variable. Two, we read one value (or a single line of values) at a time, whereas by default in Matlab, you may read many values at once.

The basic steps for using a File in C are always the same:

Create a variable of type "FILE*".

Open the file using the "fopen" function and assign the "file" to the variable.

Check to make sure the file was successfully opened by checking to see if the variable == NULL. If it does, an error has occured.

Use the fprintf or fscanf functions to write/read from the file. Usually these function calls are placed in a loop. In the case of reading data, usually, the data is read in and placed in an array, but sometimes we process the data "on the fly" (i.e., we do not store the data, we process it and create a result directly before reading any more data.

Example Code

Here are examples of the basic syntax for opening a file and writing to or reading from it:

Here is a comparison between reading from a file in Matlab and in C:

FGETS function: Read One Line at a Time

To read one line from a file (or the keyboard) at a time, use the fgets function.

fgets places the "\n" (newline) at the end of the line. Thus if we type in "hello", what really goes into the variable line is [ 'h', 'e', 'l', 'l', 'o', '\n', '\0' ]

fgets returns the keyword null on error. Thus we often use:

cppreference.com

File input/output.

The <stdio.h> header provides generic file operation support and supplies functions with narrow character input/output capabilities.

The <wchar.h> header supplies functions with wide character input/output capabilities.

I/O streams are denoted by objects of type FILE that can only be accessed and manipulated through pointers of type FILE * . Each stream is associated with an external physical device (file, standard input stream, printer, serial port, etc).

[ edit ] Types

[ edit ] predefined standard streams, [ edit ] functions, [ edit ] macro constants, [ edit ] references.

  • C23 standard (ISO/IEC 9899:2023):
  • 7.21 Input/output <stdio.h> (p: TBD)
  • 7.29 Extended multibyte and wide character utilities <wchar.h> (p: TBD)
  • 7.31.11 Input/output <stdio.h> (p: TBD)
  • 7.31.16 Extended multibyte and wide character utilities <wchar.h> (p: TBD)
  • K.3.5 Input/output <stdio.h> (p: TBD)
  • C17 standard (ISO/IEC 9899:2018):
  • C11 standard (ISO/IEC 9899:2011):
  • 7.21 Input/output <stdio.h> (p: 296-339)
  • 7.29 Extended multibyte and wide character utilities <wchar.h> (p: 402-446)
  • 7.31.11 Input/output <stdio.h> (p: 456)
  • 7.31.16 Extended multibyte and wide character utilities <wchar.h> (p: 456)
  • K.3.5 Input/output <stdio.h> (p: 586-603)
  • C99 standard (ISO/IEC 9899:1999):
  • 7.19 Input/output <stdio.h> (p: 262-305)
  • 7.24 Extended multibyte and wide character utilities <wchar.h> (p: 348-392)
  • 7.26.9 Input/output <stdio.h> (p: 402)
  • 7.26.12 Extended multibyte and wide character utilities <wchar.h> (p: 402)
  • C89/C90 standard (ISO/IEC 9899:1990):
  • 4.9 INPUT/OUTPUT <stdio.h>
  • 4.13.6 Input/output <stdio.h>

[ edit ] See also

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  • C++ Language
  • Ascii Codes
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  • Numerical Bases

Introduction

Basics of c++.

  • Structure of a program
  • Variables and types
  • Basic Input/Output

Program structure

  • Statements and flow control
  • Overloads and templates
  • Name visibility

Compound data types

  • Character sequences
  • Dynamic memory
  • Data structures
  • Other data types
  • Classes (I)
  • Classes (II)
  • Special members
  • Friendship and inheritance
  • Polymorphism

Other language features

  • Type conversions
  • Preprocessor directives

Standard library

Input/output with files.

  • ofstream : Stream class to write on files
  • ifstream : Stream class to read from files
  • fstream : Stream class to both read and write from/to files.

Open a file

Closing a file, checking state flags, get and put stream positioning, tellg() and tellp(), seekg() and seekp(), binary files, buffers and synchronization.

  • When the file is closed: before closing a file, all buffers that have not yet been flushed are synchronized and all pending data is written or read to the physical medium.
  • When the buffer is full: Buffers have a certain size. When the buffer is full it is automatically synchronized.
  • Explicitly, with manipulators: When certain manipulators are used on streams, an explicit synchronization takes place. These manipulators are: flush and endl .
  • Explicitly, with member function sync(): Calling the stream's member function sync() causes an immediate synchronization. This function returns an int value equal to -1 if the stream has no associated buffer or in case of failure. Otherwise (if the stream buffer was successfully synchronized) it returns 0 .

write(2) — Linux manual page

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Codeforwin

C program to create a file and write data into file

Quick links.

  • How to create file?
  • Example program

Write a C program to create a file and write contents in it. How to create a file in C programming? C program to input a string from user and store it in a text file. Learn how to create a file and write contents to it in C programming.

Required knowledge

Basic input and output , Pointers , Structures, File handling

How to create a file in C?

C programming provides built-in support to create, read, write and append data to file. To perform any operation on file we use a built-in FILE structure. You need to create pointer to FILE type. The pointer to FILE type will hold a logical reference to our physically existed file on disk (hard disk).

In this post I will only explain how to create a file and write data into file. Step by step descriptive logic to create a file and write data into file.

  • Declare a FILE type pointer variable to store reference of file, say FILE * fPtr = NULL; .
  • Input data from user to write into file, store it to some variable say data .
  • Finally after completing all operations you must close file, to save data written on file. Use fclose(fPtr) function to close file.

I have restricted context of this post to create a file and store data into file. Hence there will be no output on console. Alternatively, you can view file contents by opening the newly created file in your favourite text editor.

Program to create a file and write data into file

Open newly created file in your favourite text editor to view saved changes. In next post we will learn to read file contents to C program.

Create and write content to file in C

Happy coding 😉

Recommended programs to practice

  • File handling exercises index.
  • C program to read a file and print its content.
  • C program to read numbers from a file and write even, odd and prime numbers in separate file.
  • C program to append data into a file.
  • C program to compare two files.
  • C program to copy contents from one file to another file.
  • C program to read and merge two files in single file.
  • Search for: Toggle Search

Say What? Chat With RTX Brings Custom Chatbot to NVIDIA RTX AI PCs

Chatbots are used by millions of people around the world every day, powered by NVIDIA GPU-based cloud servers. Now, these groundbreaking tools are coming to Windows PCs powered by NVIDIA RTX for local, fast, custom generative AI .

Chat with RTX , now free to download , is a tech demo that lets users personalize a chatbot with their own content, accelerated by a local NVIDIA GeForce RTX 30 Series GPU or higher with at least 8GB of video random access memory, or VRAM.

Ask Me Anything

Chat with RTX uses retrieval-augmented generation (RAG), NVIDIA TensorRT-LLM software and NVIDIA RTX acceleration to bring generative AI capabilities to local, GeForce-powered Windows PCs. Users can quickly, easily connect local files on a PC as a dataset to an open-source large language model like Mistral or Llama 2, enabling queries for quick, contextually relevant answers.

Rather than searching through notes or saved content, users can simply type queries. For example, one could ask, “What was the restaurant my partner recommended while in Las Vegas?” and Chat with RTX will scan local files the user points it to and provide the answer with context.

The tool supports various file formats, including .txt, .pdf, .doc/.docx and .xml. Point the application at the folder containing these files, and the tool will load them into its library in just seconds.

Users can also include information from YouTube videos and playlists. Adding a video URL to Chat with RTX allows users to integrate this knowledge into their chatbot for contextual queries. For example, ask for travel recommendations based on content from favorite influencer videos, or get quick tutorials and how-tos based on top educational resources.

write at file c

Since Chat with RTX runs locally on Windows RTX PCs and workstations, the provided results are fast — and the user’s data stays on the device. Rather than relying on cloud-based LLM services, Chat with RTX lets users process sensitive data on a local PC without the need to share it with a third party or have an internet connection.

In addition to a GeForce RTX 30 Series GPU or higher with a minimum 8GB of VRAM, Chat with RTX requires Windows 10 or 11, and the latest NVIDIA GPU drivers.

Editor’s note: We have identified an issue in Chat with RTX that causes installation to fail when the user selects a different installation directory. This will be fixed in a future release. For the time being, users should use the default installation directory (“C:\Users\<username>\AppData\Local\NVIDIA\ChatWithRTX”).

Develop LLM-Based Applications With RTX

Chat with RTX shows the potential of accelerating LLMs with RTX GPUs. The app is built from the TensorRT-LLM RAG developer reference project, available on GitHub . Developers can use the reference project to develop and deploy their own RAG-based applications for RTX, accelerated by TensorRT-LLM. Learn more about building LLM-based applications .

Enter a generative AI-powered Windows app or plug-in to the NVIDIA Generative AI on NVIDIA RTX developer contest, running through Friday, Feb. 23, for a chance to win prizes such as a GeForce RTX 4090 GPU, a full, in-person conference pass to NVIDIA GTC and more.

Learn more about Chat with RTX .

NVIDIA websites use cookies to deliver and improve the website experience. See our cookie policy for further details on how we use cookies and how to change your cookie settings.

'ZDNET Recommends': What exactly does it mean?

ZDNET's recommendations are based on many hours of testing, research, and comparison shopping. We gather data from the best available sources, including vendor and retailer listings as well as other relevant and independent reviews sites. And we pore over customer reviews to find out what matters to real people who already own and use the products and services we’re assessing.

When you click through from our site to a retailer and buy a product or service, we may earn affiliate commissions. This helps support our work, but does not affect what we cover or how, and it does not affect the price you pay. Neither ZDNET nor the author are compensated for these independent reviews. Indeed, we follow strict guidelines that ensure our editorial content is never influenced by advertisers.

ZDNET's editorial team writes on behalf of you, our reader. Our goal is to deliver the most accurate information and the most knowledgeable advice possible in order to help you make smarter buying decisions on tech gear and a wide array of products and services. Our editors thoroughly review and fact-check every article to ensure that our content meets the highest standards. If we have made an error or published misleading information, we will correct or clarify the article. If you see inaccuracies in our content, please report the mistake via this form .

How to use Copilot Pro to write, edit, and analyze your Word documents

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Microsoft's Copilot Pro AI offers a few benefits for $20 per month. But the most helpful one is the AI-powered integration with the different Microsoft 365 apps. For those of you who use Microsoft Word, for instance, Copilot Pro can help you write and revise your text, provide summaries of your documents, and answer questions about any document.

First, you'll need a subscription to either Microsoft 365 Personal or Family . Priced at $70 per year, the Personal edition is geared for one individual signed into as many as five devices. At $100 per year, the Family edition is aimed at up to six people on as many as five devices. The core apps in the suite include Word, Excel, PowerPoint, Outlook, and OneNote.

Also: Microsoft Copilot vs. Copilot Pro: Is the subscription fee worth it?

Second, you'll need the subscription to Copilot Pro if you don't already have one. To sign up, head to the Copilot Pro website . Click the Get Copilot Pro button. Confirm the subscription and the payment. The next time you use Copilot on the website, in Windows, or with the mobile apps, the Pro version will be in effect.

How to use Copilot Pro in Word

1. open word.

Launch Microsoft Word and open a blank document. Let's say you need help writing a particular type of document and want Copilot to create a draft. 

Also: Microsoft Copilot Pro vs. OpenAI's ChatGPT Plus: Which is worth your $20 a month?

A small "Draft with Copilot" window appears on the screen. If you don't see it, click the tiny "Draft with Copilot icon in the left margin."

 width=

2. Submit your request

At the text field in the window, type a description of the text you need and click the "Generate" button.

 width=

Submit your request.

3. Review the response and your options

Copilot generates and displays its response. After reading the response, you're presented with a few different options.

 width=

Review the response and your options.

4. Keep, regenerate, or remove the draft

If you like the draft, click "Keep it." The draft is then inserted into your document where you can work with it. If you don't like the draft, click the "Regenerate" button, and a new draft is created. 

Also: What is Copilot (formerly Bing Chat)? Here's everything you need to know

If you'd prefer to throw out the entire draft and start from scratch, click the trash can icon.

 width=

Keep, regenerate, or remove the draft.

5. Alter the draft

Alternatively, you can try to modify the draft by typing a specific request in the text field, such as "Make it more formal," "Make it shorter," or "Make it more casual."

 width=

Alter the draft.

6. Review the different versions

If you opt to regenerate the draft, you can switch between the different versions by clicking the left or right arrow next to the number. You can then choose to keep the draft you prefer.

 width=

7. Revise existing text

Copilot will also help you fine-tune existing text. Select the text you want to revise. Click the Copilot icon in the left margin and select "Rewrite with Copilot."

 width=

Revise existing text.

8. Review the different versions

Copilot creates a few different versions of the text. Click the arrow keys to view each version.

 width=

Review the different versions.

9. Replace or Insert

If you find one you like, click "Replace" to replace the text you selected. 

Also: ChatGPT vs. Microsoft Copilot vs. Gemini: Which is the best AI chatbot?

Click "Insert below" to insert the new draft below the existing words so you can compare the two.

 width=

Replace or Insert.

10. Adjust the tone

Click "Regenerate" to ask Copilot to try again. Click the "Adjust Tone" button and select a different tone to generate another draft.

 width=

Adjust the tone.

11. Turn text into a table

Sometimes you have text that would look and work better as a table. Copilot can help. Select the text you wish to turn into a table. Click the Copilot icon and select "Visualize as a Table."

 width=

Turn text into a table.

12. Respond to the table

In response, click "Keep it" to retain the table. Click "Regenerate" to try again. Click the trash can icon to delete it. Otherwise, type a request in the text field, such as "remove the second row" or "make the last column wider."

 width=

Respond to the table.

13. Summarize a document

Copilot Pro can provide a summary of a document with its key points. To try this, open the document you want to summarize and then click the Copilot icon on the Ribbon. 

Also: The best AI chatbots

The right sidebar displays several prompts you can use to start your question. Click the one for "Summarize this doc."

 width=

Summarize a document.

14. Review the summary

View the generated summary in the sidebar. If you like it as is, click the "Copy" button to copy the summary and paste it elsewhere.

 width=

Review the summary.

15. Revise the summary

Otherwise, choose one of the suggested questions or ask your own question to revise the summary. For example, you could tell Copilot to make the summary longer, shorter, more formal, or less formal. 

Also: The best AI image generators

You could also ask it to expand on one of the points in the summary or provide more details on a certain point. A specific response is then generated based on your request.

 width=

Revise the summary.

16. Ask questions about a document

Next, you can ask specific questions about any of the content in a document. Again, click the Copilot icon to display the sidebar. In the prompt area, type and submit your question. Copilot displays the response in the sidebar. You can then ask follow-up questions as needed.

 width=

Ask questions about a document.

More how-tos

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I've tried Vision Pro and other top XR headsets and here's the one most people should buy

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The best AI image generators to try right now

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The best TVs of 2024: Expert tested

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Read/Write Structure From/to a File in C

  • C Program to print contents of file
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  • What is the difference between printf, sprintf and fprintf?
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For writing in the file, it is easy to write string or int to file using fprintf and putc , but you might have faced difficulty when writing contents of the struct. fwrite and fread make tasks easier when you want to write and read blocks of data.

Writing Structure to a File using fwrite

We can use fwrite() function to easily write a structure in a file. fwrite() function writes the to the file stream in the form of binary data block.

Syntax of fwrite()

  • ptr: pointer to the block of memory to be written.
  • size: the size of each element to be written (in bytes).
  • nmemb: umber of elements.
  • stream : FILE pointer to the output file stream.

Return Value

  • Number of objects written.

Reading Structure from a File using fread

We can easily read structure from a file using fread() function. This function reads a block of memory from the given stream.

Syntax of fread()

  • ptr: pointer to the block of memory to read.
  • size: the size of each element to read(in bytes).
  • nmemb: number of elements.
  • stream : FILE pointer to the input file stream.

Related Articles:

  • Structure in C

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write at file c

Azure File Sync Agent v17.1 Release - February 2024 (Security-only update)

This article describes the improvements and issues that are fixed in the Azure File Sync Agent v17.1 release that is dated February 2024. Additionally, this article contains installation instructions for this release.

Improvements and issues that are fixed

Fixes an issue that might allow unauthorized users to create new files in locations they are not allowed to. This is a security-only update. For more information about this vulnerability, see CVE-2024-21397 .

More information about the Azure File Sync Agent v17.1 release

This security update is available for Windows Server 2012 R2, Windows Server 2016, Windows Server 2019, and Windows Server 2022 installations.

The agent version for this release is 17.1.0.0.

How to obtain and install the Azure File Sync Agent 

The Azure File Sync agent is available from Microsoft Update & Microsoft Update Catalog.

Agent v17.1 version is only for upgrades for existing agent installations with agent version v17 and will not be available in Microsoft Download Center.

To update existing agent installations, download and install the update from Microsoft Update or Microsoft Update Catalog.

AfsUpdate.exe will not work for v17.1 agent installation.

Microsoft Update

To obtain and install from Microsoft Update, follow these steps on a server that has Azure File Sync agent installed:

Windows Server 2022, Server 2019 and Server2016

Click Start, and then click Settings.

In Settings, click Update & security.

In the Windows Update window, click Check online for updates from Microsoft Update.

Verify the Azure File Sync agent update is listed and then click Install now.

Server 2012 R2

Click Start, and then click Control Panel.

In Control Panel, double-click Windows Update.

In the Windows Update window, click Check for updates.

Click Important updates are available.

Verify the Azure File Sync agent update is selected, and then click Install.

Microsoft Update Catalog

Go to the following website to manually download this update from the Microsoft Update Catalog:

Azure File Sync Agent v17.1 release: February 2024 (KB5023054)

To manually install the update package, extract the cab file and run the following command from an elevated command prompt:

msiexec.exe /p packagename.msp REINSTALLMODE=OMUS REINSTALL=StorageSyncAgent,StorageSyncAgentAzureFileSync,StorageSyncAgentGuardFilter,StorageSyncAgentUpdater /qb /l*v KB5023054.log

For example, to install the Azure File Sync agent update for Server 2016, run the following command:

msiexec.exe /p StorageSyncAgent_WS2016_KB5023054.msp REINSTALLMODE=OMUS REINSTALL=StorageSyncAgent,StorageSyncAgentAzureFileSync,StorageSyncAgentGuardFilter,StorageSyncAgentUpdater /qb /l*v KB5023054.log

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IMAGES

  1. How to Create, Read and Write to a File in C++

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  2. How To Read And Write To Text File C Tutorial Visual

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  3. C++ write file

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  4. File Handling in C

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  6. HOW TO WRITE TO A FILE C PROGRAM

    write at file c

VIDEO

  1. C# Tutorial: How to Create and Write in a Text File In C#

  2. C# Tutorial

  3. How to read text file in C# Windows form application

  4. Read Text File in C++

  5. write file activity in tibco

  6. Files in C

COMMENTS

  1. C Files I/O: Opening, Reading, Writing and Closing a file

    1. Text files Text files are the normal .txt files. You can easily create text files using any simple text editors such as Notepad. When you open those files, you'll see all the contents within the file as plain text. You can easily edit or delete the contents.

  2. C Write To Files

    C Write To Files Previous Next Write To a File Let's use the w mode from the previous chapter again, and write something to the file we just created. The w mode means that the file is opened for writing. To insert content to it, you can use the fprintf () function and add the pointer variable ( fptr in our example) and some text: Example

  3. Basics of File Handling in C

    Courses Practice File handing in C is the process in which we create, open, read, write, and close operations on a file. C language provides different functions such as fopen (), fwrite (), fread (), fseek (), fprintf (), etc. to perform input, output, and many different C file operations in our program. Why do we need File Handling in C?

  4. File Handling in C

    In C, we use a structure pointer of a file type to declare a file: FILE *fp; C provides a number of build-in function to perform basic file operations: fopen () - create a new file or open a existing file fclose () - close a file getc () - reads a character from a file putc () - writes a character to a file

  5. How to Write to File in C?

    How to Write to File in C? C - Write to File When a programs output or some of the variables has to be saved to a storage location on file system, the data has to be written to a file. In this tutorial, we shall learn how to write data to a file using some of the builtin functions of C programming language.

  6. C Files I/O: Create, Open, Read, Write and Close a File

    Whenever you want to work with a file, the first step is to create a file. A file is nothing but space in a memory where data is stored. To create a file in a 'C' program following syntax is used, FILE *fp; fp = fopen ("file_name", "mode"); In the above syntax, the file is a data structure which is defined in the standard library.

  7. C

    What are files in C? A file is used to store huge data. C provides multiple file management functions like file creation, opening and reading files, Writing to the file, and closing a file. The file is used to store relevant data and file handling in C is used to manipulate the data. Types of Files in C

  8. C

    There are various functions provided by C standard library to read and write a file, character by character, or in the form of a fixed length string. Writing a File Following is the simplest function to write individual characters to a stream − int fputc ( int c, FILE *fp );

  9. C Files

    In C, you can create, open, read, and write to files by declaring a pointer of type FILE, and use the fopen () function: FILE *fptr fptr = fopen (filename, mode); FILE is basically a data type, and we need to create a pointer variable to work with it ( fptr ). For now, this line is not important.

  10. How to write in a file using fputs() in C

    Courses. fputs () is a function declared in stdio.h header file. It is used to write the contents of the file. The function takes 2 arguments. The first argument is a pointer to the string which is to be written and the second argument is the pointer of the file where the string is to be written. It returns 1 if the write operation was ...

  11. C Programming

    File Input and Output in C. In order to read information from a file, or to write information to a file, your program must take the following actions. 1) Create a variable to represent the file. 2) Open the file and store this "file" with the file variable. 3) Use the fprintf or fscanf functions to write/read from the file.

  12. How to Create, Read and Write to a File in C Programming

    In this video we will learn Create, Read and Write to a text File in C Programming with examples. C Files I/O: Opening, Reading, Writing and Closing a file. ...

  13. c

    How can I write a little piece of text into a .txt file? I've been Googling for over 3-4 hours, but can't find out how to do it. fwrite(); has so many arguments, and I don't know how to use it. What's the easiest function to use when you only want to write a name and a few numbers to a .txt file?

  14. File input/output

    The <stdio.h> header provides generic file operation support and supplies functions with narrow character input/output capabilities.. The <wchar.h> header supplies functions with wide character input/output capabilities.. I/O streams are denoted by objects of type FILE that can only be accessed and manipulated through pointers of type FILE *.Each stream is associated with an external physical ...

  15. Input/output with files

    Tutorials C++ Language Input/output with files Input/output with files C++ provides the following classes to perform output and input of characters to/from files: ofstream: Stream class to write on files ifstream: Stream class to read from files fstream: Stream class to both read and write from/to files.

  16. write(2)

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    Convert the System::String (.NET) to std::string (native C++). This is demonstrated here. After the conversion you can write it to the file using std::ofstream as you attempted. Use .NET APIs for writing the file, for example with FileStream and StreamWriter, as demonstrated below:

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  23. Create a form in Word that users can complete or print

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