Write a program that, when run, will print out its source code?

Question

Code should compile and print out itself.

Answer 1

Assume the source code file name is "example.c", below code might help you.

#include <stdio.h>

int main()
{
    FILE *fp = NULL;
    int c;

    fp = fopen("example.c", "r");
    if (fp == NULL) {
        printf("Unable to open the source code.\n");
        return 0;
    }

    while((c = fgetc(fp)) != EOF)
        fputc(c, stderr);

    fclose(fp);
    return 0;
}

Answer 2

Self printing program is called Quines and you can find many solution on the web, one is what Arshad has suggested another one you can find here -

#include <stdio.h>
#define d "\\"
#define c "\n"
#define b "\""
#define a "#include <stdio.h>%s#define d %s%s%s%s%s#define c %s%sn%s%s#define b %s%s%s%s%s#define a %s%s%s%smain(){printf(a,c,b,d,d,b,c,b,d,b,c,b,d,b,b,c,b,a,b,c,c);}%s"
main(){printf(a,c,b,d,d,b,c,b,d,b,c,b,d,b,b,c,b,a,b,c,c);}

Answer 3

Try this,

#include <stdio.h>

int main(int argc,char *argv[])
{
    if(argc != 2){
        printf("usage : exe <filename>\n");
        return 0;
    }
    char buf[100];
    sprintf(buf,"cat %s",argv[1]);
    system(buf);
    return 0;
}