C++

Reference

<type_traits>

class template
<type_traits>

std::is_const

template <class T> struct is_const;
Is const-qualified

Trait class that identifies whether T is a const-qualified type.

It inherits from integral_constant as being either true_type or false_type, depending on whether T is const.

Template parameters

T
A type.

Member types

Inherited from integral_constant:
member typedefinition
value_typebool
typeeither true_type or false_type

Member constants

Inherited from integral_constant:
member constantdefinition
valueeither true or false

Member functions

Inherited from integral_constant:
operator bool
Returns value (public member function)

Example

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// is_const example
#include <iostream>
#include <type_traits>

int main() {
  std::cout << std::boolalpha;
  std::cout << "is_const:" << std::endl;
  std::cout << "int: " << std::is_const<int>::value << std::endl;
  std::cout << "const int: " << std::is_const<const int>::value << std::endl;
  std::cout << "const int*: " << std::is_const<const int*>::value << std::endl;
  std::cout << "int* const: " << std::is_const<int* const>::value << std::endl;
  return 0;
}

Output:
is_const:
int: false
const int: true
const int*: false
int* const: true


See also

is_volatile
Is volatile-qualified (class template)
is_signed
Is signed type (class template)
is_unsigned
Is unsigned type (class template)
is_literal_type
Is literal type (class template)