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C preprocessor power

Filed Under Software, Mind benders

I was discussing with a friend the popular chalange to write a program that prints its own source. In C of course. The shortest one we found was:

main(){char*s=”main(){char*s=%c%s%c;printf(s,34,s,34);}”;printf(s,34,s,34);}

What I did not like about this one is that it relied on the knowledge that the ASCII code of the quote is 34. I wanted to find a solution that is still short, but does not have that. Preprocessor to the rescue:

#define _(__) char*a=#__;__
_(main() {printf(”#define _(__) char*a=#__;__\n_(%s)”,a);})

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