is_same-Klasse
Testet, ob zwei Typen identisch sind.
Syntax
template <class Ty1, class Ty2>
struct is_same;
Parameter
Ty1
Der erste abzufragende Typ.
Ty2
Der zweite abzufragende Typ.
Hinweise
Eine Instanz des Typprädikats enthält "true", wenn die Typen "Ty1 " und "Ty2 " denselben Typ aufweisen, andernfalls "false".
Beispiel
// std__type_traits__is_same.cpp
// compile with: /EHsc
#include <type_traits>
#include <iostream>
struct base
{
int val;
};
struct derived
: public base
{
};
int main()
{
std::cout << "is_same<base, base> == " << std::boolalpha
<< std::is_same<base, base>::value << std::endl;
std::cout << "is_same<base, derived> == " << std::boolalpha
<< std::is_same<base, derived>::value << std::endl;
std::cout << "is_same<derived, base> == " << std::boolalpha
<< std::is_same<derived, base>::value << std::endl;
std::cout << "is_same<int, int> == " << std::boolalpha
<< std::is_same<int, int>::value << std::endl;
std::cout << "is_same<int, const int> == " << std::boolalpha
<< std::is_same<int, const int>::value << std::endl;
return (0);
}
is_same<base, base> == true
is_same<base, derived> == false
is_same<derived, base> == false
is_same<int, int> == true
is_same<int, const int> == false
Anforderungen
Header:<type_traits>
Namespace: std