C program to print source code of itself as output

Write a C program to print source code of itself as output. How to print source code of itself as output in C programming.

Required knowledge

Basic Input Output, File Handling, Macros

How to print source code of itself using __FILE__ macro

Printing source code of a file is no complex. You should only bother about how to get path of current file without user input, rest is simple read and print file contents.

C programming supports various preprocessor directives (macros) for logging and exception handling. Macros such as

__FILE__ expands to path of current file.
__LINE__ expands to current line number where used.
__DATE__ expands to string pointing to today’s date.
__TIME__ expands to current time.
__FUNCTION__ expands to current function name where used. C99

To print source code of a program itself as output, you can use __FILE__ to get path of current file.

Program to print source code of itself as output

/**
 * C program to print source code of itself as output
 */

#include <stdio.h>
#include <stdlib.h>


int main()
{
    FILE *fPtr;
    
    char ch;
    

    /*
     * __FILE__ is a macro that contains path of current file.
     * Open current program in read mode. 
     */
    fPtr = fopen(__FILE__, "r");


    /* fopen() return NULL if unable to open file in given mode. */
    if (fPtr == NULL)
    {
        /* Unable to open file hence exit */
        printf("\nUnable to open file.\n");
        printf("Please check whether file exists and you have read privilege.\n");
        exit(EXIT_SUCCESS);
    }


    /* Read file character by character */
    while ((ch = fgetc(fPtr)) != EOF)
    {
        printf("%c", ch);
    }
    

    /* Close files to release resources */
    fclose(fPtr);

    return 0;
}

/**
 * C program to print source code of itself as output
 */

#include 
#include 


int main()
{
    FILE *fPtr;

    char ch;


    /*
     * __FILE__ is a macro that contains path of current file.
     * Open current program in read mode.
     */
    fPtr = fopen(__FILE__, "r");


    /* fopen() return NULL if unable to open file in given mode. */
    if (fPtr == NULL)
    {
        /* Unable to open file hence exit */
        printf("\nUnable to open file.\n");
        printf("Please check whether file exists and you have read privilege.\n");
        exit(EXIT_SUCCESS);
    }


    /* Read file character by character */
    while ((ch = fgetc(fPtr)) != EOF)
    {
        printf("%c", ch);
    }


    /* Close files to release resources */
    fclose(fPtr);

    return 0;
}

Happy coding 😉