is_const Class

Tests if type is const.

template<class Ty>
    struct is_const;

Parameters

  • Ty
    The type to query.

Remarks

An instance of the type predicate holds true if Ty is const-qualified.

Example

// std_tr1__type_traits__is_const.cpp 
// compile with: /EHsc 
#include <type_traits> 
#include <iostream> 

struct trivial 
    { 
    int val; 
    }; 

int main() 
    { 
    std::cout << "is_const<trivial> == " << std::boolalpha 
        << std::is_const<trivial>::value << std::endl; 
    std::cout << "is_const<const trivial> == " << std::boolalpha 
        << std::is_const<const trivial>::value << std::endl; 
    std::cout << "is_const<int> == " << std::boolalpha 
        << std::is_const<int>::value << std::endl; 
    std::cout << "is_const<const int> == " << std::boolalpha 
        << std::is_const<const int>::value << std::endl; 

    return (0); 
    } 
is_const<trivial> == false
is_const<const trivial> == true
is_const<int> == false
is_const<const int> == true

Requirements

Header: <type_traits>

Namespace: std

See Also

Reference

<type_traits>

is_volatile Class