C Program to Display same Source Code as Output

Program :

#include<stdio.h>

int main(){
    FILE *fp;
    char c;

    fp = fopen(__FILE__,"r");

    do{
         c= getc(fp);
         putchar(c);
    }
    while(c!=EOF);

    fclose(fp);

    return 0;
}

Output :

#include<stdio.h>

int main(){
    FILE *fp;
    char c;

    fp = fopen(__FILE__,"r");

    do{
         c= getc(fp);
         putchar(c);
    }
    while(c!=EOF);

    fclose(fp);

    return 0;
}

Explanation :

fp = fopen(__FILE__,"r");

[arrowlist]

• __FILE__ is Standard Predefined Macros in C Programming.
• This macro will expand to the name of current file path.
• Suppose we have saved this source code at path -

[/arrowlist]

c://tc/bin/file1.c

then

fp = fopen(__FILE__,"r");

will be expanded as -

fp = fopen("c://tc/bin/file1.c","r");