C++

Reference

<type_traits>

class template
<type_traits>

std::is_void

template <class T> struct is_void;
Is void

Trait class that identifies whether T is void.

It inherits from integral_constant as being either true_type or false_type: It is true_type when T is void or a cv-qualified void type, and false_type in any other case.

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_void example
#include <iostream>
#include <type_traits>

int main() {
  std::cout << std::boolalpha;
  std::cout << "is_void:" << std::endl;
  std::cout << "int: " << std::is_void<int>::value << std::endl;
  std::cout << "void: " << std::is_void<void>::value << std::endl;
  return 0;
}

Output:
is_void:
int: false
void: true


See also

is_empty
Is empty class (class template)
is_fundamental
Is fundamental type (class template)