std::conditional
From Get docs
Cpp/docs/latest/types/conditional
std::conditional
Defined in header <type_traits>
|
||
---|---|---|
|
(since C++11) |
Provides member typedef type
, which is defined as T
if B
is true
at compile time, or as F
if B
is false
.
Member types
Member type | Definition |
---|---|
type
|
T if B == true , F if B == false
|
Helper types
|
(since C++14) |
Possible implementation
|
Example
#include <iostream>
#include <type_traits>
#include <typeinfo>
int main()
{
typedef std::conditional<true, int, double>::type Type1;
typedef std::conditional<false, int, double>::type Type2;
typedef std::conditional<sizeof(int) >= sizeof(double), int, double>::type Type3;
std::cout << typeid(Type1).name() << '\n';
std::cout << typeid(Type2).name() << '\n';
std::cout << typeid(Type3).name() << '\n';
}
Possible output:
int
double
double
See also
(C++11) |
hides a function overload or template specialization based on compile-time boolean (class template) |
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