is_void Class

Tests whether the type is void.

Syntax

template <class T>
struct is_void;

Parameters

T
The type to query.

Remarks

An instance of the type predicate holds true if the type T is void or a cv-qualified form of void, otherwise it holds false.

Example

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

struct trivial
    {
    int val;
    };

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

    return (0);
    }

is_void<trivial> == false
is_void<void()> == false
is_void<void> == true

Requirements

Header: <type_traits>

Namespace: std

See also

<type_traits>