#include <limits>
// ...
int a = std::numeric_limits<int>::max();
size_t INF_SPECIAL = ((size_t) ~0); // generates all 1's
int INF_INT = std::numeric_limits<int>::max(); // #include <limits>
double INF_DOUBLE = std::numeric_limits<double>::infinity();
#include <limits>
// ...
int a = std::numeric_limits<int>::infinity();