RAND_MAX
From cppreference.com
Defined in header <stdlib.h>


#define RAND_MAX /*implementation defined*/ 

Expands to an integer constant expression equal to the maximum value returned by the function rand(). This value is implementation dependent. It's guaranteed that this value is at least 32767.
[edit] See also
generates a pseudorandom number (function)  
seeds pseudorandom number generator (function)  
C++ documentation for RAND_MAX
