is_void Class

 

The latest version of this topic can be found at 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>