is_void Class

 

Tests whether the type is void.

template<class T>
    struct is_void;

T

The type to query.

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

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