How to check that template's parameter type is integral?

Question

In the description of some std template function I saw something like:

if the template parameter is of integral type, the behavior is such and such.

Answer 1

One possibility:

#include  
#include  

struct trivial 
{ 
    int val; 
}; 

int main() 
{ 
    std::cout << "is_integral == " << std::boolalpha 
        << std::is_integral::value << std::endl; 
    std::cout << "is_integral == " << std::boolalpha 
        << std::is_integral::value << std::endl; 
    std::cout << "is_integral == " << std::boolalpha 
        << std::is_integral::value << std::endl; 

    return (0); 
} 

So you then use std::is_integral<> to determine the action.