After reading Hidden Features and Dark Corners of C++/STL on comp.lang.c++.moderated, I was completely surprised that it compiled and worked in both Visual Studio 2008 and G++ 4.4.

The code:

#include <stdio.h>
int main()
{
     int x = 10;
     while( x --> 0 ) // x goes to 0
     {
       printf("%d ", x);
     }
}

I’d assume this is C, since it works in GCC as well. Where is this defined in the standard, and where has it come from?

GManNickG

Answer:

That’s not an operator -->. That’s two separate operators, -- and >.

The condition code is decrementing x, while returning x‘s original (not decremented) value, and then comparing the original value with 0 using the > operator.

To better understand, the statement could be written as follows:

while( (x--) > 0 )

Potatoswatter

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