std:: signed_integral

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

注释

signed_integral<T> 可能被非 有符号整数类型 的类型所满足，例如 char （在 char 为有符号类型的系统上）。

示例

#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
}

(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

参见