std::unsigned_integral

 

C++

编译器支持

自立实现与有宿主实现

语言

标准库

标准库标头

具名要求

功能特性测试宏 (C++20)

语言支持库

概念库 (C++20)

诊断库

内存管理库

元编程库 (C++11)

通用工具库

容器库

迭代器库

范围库 (C++20)

算法库

字符串库

文本处理库

数值库

日期和时间库

输入/输出库

文件系统库 (C++17)

并发支持库 (C++11)

执行控制库 (C++26)

技术规范

符号索引

外部库

 

概念库

核心语言概念 same_as (C++20) derived_from (C++20) convertible_to (C++20) common_reference_with (C++20) common_with (C++20) integral (C++20) signed_integral (C++20) unsigned_integral (C++20) floating_point (C++20) swappableswappable_with (C++20)(C++20) destructible (C++20) constructible_from (C++20) default_initializable (C++20)   move_constructible (C++20) copy_constructible (C++20) assignable_from (C++20)

比较概念 equality_comparableequality_comparable_with (C++20)(C++20) totally_orderedtotally_ordered_with (C++20)(C++20) 对象概念 movable (C++20) copyable (C++20) semiregular (C++20) regular (C++20) 可调用概念 invocableregular_invocable (C++20)(C++20) predicate (C++20) relation (C++20) equivalence_relation (C++20) strict_weak_order (C++20)

仅用于阐释的概念 boolean-testable  (C++20)

 

<tbody> </tbody>

在标头 <concepts> 定义
template < class T > concept unsigned_integral = std::integral<T> && !std::signed_integral<T>;		(C++20 起)

See More

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

注解

unsigned_integral<T> 可以不为有符号整数类型，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);               // signed
    test(0xFULL, "0xFULL"); // unsigned
    test('A');              // platform-dependent
    test(true, "true");     // unsigned
    test(4e-2, "4e-2");     // non-integral (hex-float)
    test("∫∫");             // non-integral
}

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

引用

• C++23 标准（ISO/IEC 14882:2024）：

• 18.4.7 Arithmetic concepts [concepts.arithmetic]

• C++20 标准（ISO/IEC 14882:2020）：

• 18.4.7 Arithmetic concepts [concepts.arithmetic]

参阅

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