Clex on Write a program that makes 2 + 2 = 5

Comment on Write a program that makes 2 + 2 = 5

Here's mine :

    $ cat test.c
    #include <stdio.h>
    
    int main() {
        int a = 3;
        int b = 3;
    
        // aren't we supposed to add 2 and 2 ??/
        a = 2;
        b = 2;
    
        printf("%d\n", a + b);
    
        return 0;
    }
    $ gcc -W -Wall -trigraphs test2.c 2>/dev/null
    $ ./a.out
    5
    $

gizmo686 12y

Is the trick here the "-trigraphs" flag, or the fact that you are showing us test.c but compiling test2.c? Both approaches seem like they should work.

cdcarter 12y

It's the trigraph ??/ which translates to a \.

gizmo686 12y

The trigraph appears in the file "test.c". If you look at the compilation command, you will see that that is not the file that is actually compiled.

cbsmith 12y

If you compile "test.c" you will see that that isn't relevant issue.

tbirdz 12y

Very sneaky. For anyone else wondering why this works, look up trigraphs.

vidarh 12y

And after looking it up, you better then realise that if you actually ever use them in production code you better have a really good reason, or your colleagues will forever curse your name..

I think the above is probably the first time I've seen trigraphs used in the last 20 years or so.

adito 12y

http://en.wikipedia.org/wiki/Digraphs_and_trigraphs#C

sorry for spoiling:

"??/" got replaced by "\"

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