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std:: unsigned_integral

From cppreference.net
C++
Concepts library
Exposition-only concepts
 (C++20)
定义于头文件 <concepts>
template < class T >
concept unsigned_integral = std:: integral < T > && ! std:: signed_integral < T > ;
(C++20 起)

当且仅当 T 为整数类型且 std:: is_signed_v < T > 为 false 时，概念 unsigned_integral<T> 得到满足。

目录

注释

unsigned_integral<T> 可能被并非 无符号整数类型 的类型所满足，例如 bool 。

示例

运行此代码 
#include <concepts>
#include <iostream>
#include <string_view>
void test(std::signed_integral auto x, std::string_view text = "")
{
    std::cout << text << " (" + (text == "") << x << ") is a signed integral\n";
}
void test(std::unsigned_integral auto x, std::string_view text = "")
{
    std::cout << text << " (" + (text == "") << x << ") is an unsigned integral\n";
}
void test(auto x, std::string_view text = "")
{
    std::cout << text << " (" + (text == "") << x << ") is non-integral\n";
}
int main()
{
    test(42);               // 有符号
    test(0xFULL, "0xFULL"); // 无符号
    test('A');              // 平台相关
    test(true, "true");     // 无符号
    test(4e-2, "4e-2");     // 非整型（十六进制浮点数）
    test("∫∫");             // 非整型
}

可能的输出： 

(42) is a signed integral
0xFULL (15) is an unsigned integral
(A) is a signed integral
true (1) is an unsigned integral
4e-2 (0.04) is non-integral
(∫∫) is non-integral

参考文献

  • C++23 标准 (ISO/IEC 14882:2024):
  • 18.4.7 算术概念 [concepts.arithmetic]
  • C++20 标准 (ISO/IEC 14882:2020):
  • 18.4.7 算术概念 [concepts.arithmetic]

另请参阅

(C++11)
检查类型是否为整型
(类模板)
(C++11)
检查类型是否为有符号算术类型
(类模板)