Strange C++ errors with code that has min()/max() calls

I'm seeing strange errors when my C++ code has min() or max() calls. I'm using Visual C++ compilers.

18.08.2008 04:13:34
This is officially the oddest question on Stack Overflow
eplawless 18.08.2008 04:16:58
6 ОТВЕТОВ
РЕШЕНИЕ

Check if your code is including the windows.h header file and either your code or other third-party headers have their own min()/max() definitions. If yes, then prepend your windows.h inclusion with a definition of NOMINMAX like this:

#define NOMINMAX
#include <windows.h>
18
18.08.2008 04:15:34

Ugh... scope it, dude: std::min(), std::max().

1
18.08.2008 04:20:09
You still need to #define NOMINMAX or the preprocessor will still expand min & max.
Ferruccio 11.09.2008 01:49:36

I haven't used it in years but from memory boost assigns min and max too, possibly?

0
18.08.2008 04:49:15

Another possibility could be from side effects. Most min/max macros will include the parameters multiple times and may not do what you expect. Errors and warnings could also be generated.

max(a,i++) expands as ((a) > (i++) ? (a) : (i++))

afterwards i is either plus 1 or plus 2

The () in the expansion are to avoid problems if you call it with formulae. Try expanding max(a,b+c)

2
23.08.2008 11:17:25

Honestly, when it comes to min/max, I find it best to just define my own:

#define min(a,b) ((a) < (b) ? (a) : (b))
#define max(a,b) ((a) >= (b) ? (a) : (b))
0
19.08.2011 17:39:24
Which, frankly, is asking for trouble. In C++, use using std::swap and write your own swap when you can do better than the default. In C, at the very lease write #define min(a,b) ((a) < (b) ? (a) : (b)) and MAKE SURE YOU DON'T CALL IT WITH ANYTHING WITH SIDE EFFECTS, because you will have multiple evaluation.
David Thornley 24.11.2009 22:28:35

Since Windows defines this as a function-style macro, the following workaround is available:

int i = std::min<int>(3,5);

This works because the macro min() is expanded only when min is followed by (, and not when it's followed by <.

2
24.01.2011 14:32:20