std::is_same
std::is_same
| Defined in header | | |
|---|---|---|
| template< class T, class U > struct is_same; | | (since C++11) |
If T and U name the same type with the same const-volatile qualifications, provides the member constant value equal to true. Otherwise value is false.
Helper variable template
| template< class T, class U > inline constexpr bool is_same_v = is_same | | (since C++17) |
|---|
Inherited from std::integral_constant
Member constants
| value static | true if T and U is the same type , false otherwise (public static member constant) |
|---|
Member functions
| operator bool | converts the object to bool, returns value (public member function) |
|---|---|
| operator() (C++14) | returns value (public member function) |
Member types
| Type | Definition |
|---|---|
| value_type | bool |
| type | std::integral_constant<bool, value> |
Possible implementation
| template<class T, class U> struct is_same : std::false_type {}; template<class T> struct is_same<T, T> : std::true_type {}; |
|:----|
Example
#include <iostream>
#include <type_traits>
#include <cstdint>
void print_separator()
{
std::cout << "-----\n";
}
int main()
{
std::cout << std::boolalpha;
std::cout << std::is_same<int, int32_t>::value << '\n'; // true
std::cout << std::is_same<int, int64_t>::value << '\n'; // false
std::cout << std::is_same<float, int32_t>::value << '\n'; // false
print_separator(
std::cout << std::is_same<int, int>::value << "\n"; // true
std::cout << std::is_same<int, unsigned int>::value << "\n"; // false
std::cout << std::is_same<int, signed int>::value << "\n"; // true
print_separator(
// unlike other types 'char' is not 'unsigned' and not 'signed'
std::cout << std::is_same<char, char>::value << "\n"; // true
std::cout << std::is_same<char, unsigned char>::value << "\n"; // false
std::cout << std::is_same<char, signed char>::value << "\n"; // false
}
Output:
true
false
false
-----
true
false
true
-----
true
false
false
See also
| is_integral (C++11) | checks if a type is integral type (class template) |
|---|---|
| make_signed (C++11) | makes the given integral type signed (class template) |
| make_unsigned (C++11) | makes the given integral type unsigned (class template) |
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