What does this do?

This is a discussion on What does this do? within the C Programming forums, part of the General Programming Boards category; Just a bit of fun Code: #include <stdio.h> int main ( void ) { printf,"%d",32; return 0; } - does ...

  1. #1
    and the hat of wrongness Salem's Avatar
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    What does this do?

    Just a bit of fun
    Code:
    #include <stdio.h>
    
    int main ( void ) {
        printf,"%d",32;
        return 0;
    }
    - does it compile?
    - does it run?
    - what's the output?
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  2. #2
    Captain Crash brewbuck's Avatar
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    Yes, yes, and nothing.

  3. #3
    Frequently Quite Prolix dwks's Avatar
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    You should have used invisible text or something, so as not to spoil things for the rest of us . . .

    http://www.eskimo.com/~scs/cclass/int/sx4db.html
    dwk

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  4. #4
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    EDIT: Ok, so I wasn't supposed to compile it, sorry. I thought maybe it was some experiment or something. I guess I could do like dwks said and color my text invisible.
    Last edited by swoopy; 07-11-2007 at 09:09 PM.

  5. #5
    Frequently Quite Prolix dwks's Avatar
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    I was going to mention the warnings, but you beat me to it.

    It's kind of like doing this.
    Code:
    #include <stdio.h>
    
    int main(void) {
        printf;
        "&#37;d";
        32;
        return 0;
    }
    so you get three warnings about statements that do nothing.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


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  6. #6
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by dwks View Post
    You should have used invisible text or something, so as not to spoil things for the rest of us . . .
    Yeah. Kinda thoughtless, sorry.

  7. #7
    Frequently Quite Prolix dwks's Avatar
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    S'ok. swoopy did exactly the same thing, after all.

    What would make it more interesting would be if you used the return value.
    Code:
    int x = printf, "&#37;d", 32;
    I'm sure many people know that printf() returns the number of characters printed (but who ever uses that value?), so you might think that x is set to 2. But no, it's 32.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


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    After your first post, I thought maybe it outputted a space, so I double checked, and it did not.

  9. #9
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    Here's some more fun:
    Code:
    #include <stdio.h>
    
    int main(void)
    {
        char s[4];
        return printf(s, sprintf(s, "%s", "%*p"), printf);
    }
    - what is it printing?
    - is the same thing printed after each execution?
    - what about after recompiling?

  10. #10
    Frequently Quite Prolix dwks's Avatar
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    Answer (just guessing, I didn't compile it) in invisible text:
    - The address of printf
    - almost certainly, unless the dynamic library containing printf() was re-loaded for some reason
    - probably, unless printf was linked statically

    <end of text>

    BTW, you made me re-write my answer several times . . . very nice program.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


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  11. #11
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    jhgjhg
    Last edited by robwhit; 07-11-2007 at 08:28 PM. Reason: i suck

  12. #12
    Deathray Engineer MacGyver's Avatar
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    I agree with dwks.

  13. #13
    Woof, woof! zacs7's Avatar
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    Well that's just witchcraft

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