<type_traits>

类模板
<type_traits>

std::is_const

template <class T> struct is_const;
Is const-qualified

Trait class that identifies whether T is a const-qualified type.

它继承自 integral_constant,并根据Tis const.

模板参数

T
一个类型。

成员类型

Inherited from integral_constant
成员类型定义
value_typebool
类型true_type 或 false_type

成员常量

Inherited from integral_constant
成员常量定义
trueorfalse

成员函数

Inherited from integral_constant

示例

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// is_const example
#include <iostream>
#include <type_traits>

int main() {
  std::cout << std::boolalpha;
  std::cout << "is_const:" << std::endl;
  std::cout << "int: " << std::is_const<int>::value << std::endl;
  std::cout << "const int: " << std::is_const<const int>::value << std::endl;
  std::cout << "const int*: " << std::is_const<const int*>::value << std::endl;
  std::cout << "int* const: " << std::is_const<int* const>::value << std::endl;
  return 0;
}

输出
is_const:
int: false
const int: true
const int*: false
int* const: true


另见