Table of Contents

C fopen() Function With Examples

The fopen() method in C is a library function that functions to open a file to perform various operations which include reading, writing, etc. along with various modes. If the file exists, then the fopen() function will open the particular file a new file is created.

Syntax

FILE *fopen(const char *file_name, const char *mode_of_operation);

Parameters

The method takes two parameters, both of character pointer type:

1. file_name: This parameter, of C string type, holds the name of the file to be opened.
2. mode_of_operation: Also a C string type, this parameter indicates the mode of file access, specifying whether the file will be opened for reading, writing, or both.

 Table lists valid mode_of_operation values in C with their meaning

Return Value

• The function is used to return a pointer to FILE if the execution succeeds else NULL is returned. 

Example of fopen()

On running the following command, a new file will be created by the name “demo_file.txt” with the following content: 

// C program to illustrate fopen()
 
#include <stdio.h>
#include <stdlib.h>
 
int main()
{
 
    // pointer demo to FILE
    FILE* demo;
 
    // Creates a file "demo_file"
    // with file access as write-plus mode
    demo = fopen("demo_file.txt", "w+");
 
    // adds content to the file
    fprintf(demo, "%s %s %s", "Welcome", "to",
            "Skillvertex");
 
    // closes the file pointed by demo
    fclose(demo);
 
    return 0;
}

According to the command , a new file will be produced by the name “demo_file.txt” with the following content: 

Welcome to Skillvertex

To view the file, Run the following code, which will open the file and display its content.

// C program to illustrate fopen()
 
#include <stdio.h>
 
int main()
{
 
    // pointer demo to FILE
    FILE* demo;
    int display;
 
    // Creates a file "demo_file"
    // with file access as read mode
    demo = fopen("demo_file.txt", "r");
 
    // loop to extract every characters
    while (1) {
        // reading file
        display = fgetc(demo);
 
        // end of file indicator
        if (feof(demo))
            break;

        // displaying every characters
        printf("%c", display);
    }
 
    // closes the file pointed by demo
    fclose(demo);
 
    return 0;
}

Output

Welcome to Skillvertex

FAQ- C fopen() Function With Examples

Hridhya Manoj

Hello, I’m Hridhya Manoj. I’m passionate about technology and its ever-evolving landscape. With a deep love for writing and a curious mind, I enjoy translating complex concepts into understandable, engaging content. Let’s explore the world of tech together