PRB: Using STL in Windows Program Can Cause Min/Max Conflicts

CAUSE

The problem is caused by conflicting definitions of min and max. Min and max are defined as macros in Windef.h as follows:

   #ifndef NOMINMAX
   #ifndef max
   #define max(a,b)  (((a) > (b)) ? (a) : (b))
   #endif

   #ifndef min
   #define min(a,b)  (((a) < (b)) ? (a) : (b))
   #endif
   #endif  /* NOMINMAX */ 
				

NOTE: Windef.h is included by Windows.h, which is included in nearly every Windows-based program.

Min and max are defined as templated functions in the Standard Template Library (STL). The following definitions of min and max can be found in the file Algobase.h:

   template <class T>
   inline const T& min(const T& a, const T& b) {
       return b < a ? b : a;
   }
   template <class T, class Compare>
   inline const T& min(const T& a, const T& b, Compare comp) {
       return comp(b, a) ? b : a;
   }
   template <class T>
   inline const T& max(const T& a, const T& b) {
       return  a < b ? b : a;
   }
   template <class T, class Compare>
   inline const T& max(const T& a, const T& b, Compare comp) {
       return comp(a, b) ? b : a;
   }
				

Because the Windef.h definition is a macro, the function definitions cause syntax errors when both Windef.h (or Windows.h) and Algobase.h (from the STL) are included. The precise errors will depend on the order in which the two are compiled.