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Just for fun III - Prints self out ...

Posted on 1998-08-19
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Last Modified: 2010-04-15
Simple exercise: Program that prints itself out (Only executable version is available at runtime!!!)

Objective: a suitable add-on for copyright software? (just kidding)

There is a solution ...
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Question by:newexpert
[X]
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8 Comments
 
LVL 2

Expert Comment

by:kellyjj
ID: 1252176
Are you talking about printing source code? or the
binary???  
0
 
LVL 6

Accepted Solution

by:
snoegler earned 0 total points
ID: 1252177
#include <stdio.h>
char *text[]={"char *text[]={","%s%c%s%c,%c%s%c,%c%s%c,%c%s%c,%c%s%c,%c%s%c};%c%c","void main(){","puts(text[5]);printf(text[1],text[0],34,text[0],34,34,text[1],34,34,text[2],34,34,text[3],34,34,text[4],34,34,text[5],34,13,10);","puts(text[2]);puts(text[3]);printf(text[4]);}","#include <stdio.h>"};
void main(){
puts(text[5]);printf(text[1],text[0],34,text[0],34,34,text[1],34,34,text[2],34,34,text[3],34,34,text[4],34,34,text[5],34,13,10);
puts(text[2]);puts(text[3]);printf(text[4]);}

I've tested it, it works - but it's pretty ugly :)
0
 
LVL 84

Expert Comment

by:ozo
ID: 1252178
The standard example, fron the comp.lang.c FAQ, is:

char*s="char*s=%c%s%c;main(){printf(s,34,s,34);}";main(){printf(s,34,s,34);}
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LVL 6

Expert Comment

by:snoegler
ID: 1252179
that is a bit shorter :)
0
 
LVL 1

Author Comment

by:newexpert
ID: 1252180
How about the one I had in mind (it even does some extra things):
#include "pself.h"
PH(int main(void) {)
PA(int i; int sum = 0; for (i = 1; i <= 100; i++) sum += i;)
PB(return sum; })

The actual code that does the hard work is conveniently hidden in pself.h
#define PH(x) x puts("#include \"pself.h\"\nPH("#x")");
#define PA(x) x; puts("PA("#x")");
#define PB(x) puts("PB("#x")"); x

0
 
LVL 84

Expert Comment

by:ozo
ID: 1252181
Hmm, if you allow that, then how about just this:

#include "pself.h"

with pself.h containg:
main(){
  int i; int sum = 0;
  for (i = 1; i <= 100; i++) sum += i;
  puts("#include \"pself.h\"\n");
  return sum;
}

Or this:

X

compiled with
cc -DX='main(){puts("X");}'


0
 
LVL 1

Author Comment

by:newexpert
ID: 1252182
Good point.  Wonder how hard would it be to create a .h which source dump any .c file that includes it?
0
 
LVL 1

Author Comment

by:newexpert
ID: 1252183
Where did the last word "it" go?
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