std::nothrow

 

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nothrow

destroying_delete (C++20)

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launder (C++17)

 

在标头 <new> 定义
extern const std::nothrow_t nothrow;

std::nothrow 是 std::nothrow_t 类型的常量，用于区分抛出与不抛出分配函数的重载。

示例

运行此代码

#include <iostream>
#include <new>
 
int main()
{
    try {
        while (true) {
            new int[100000000ul];   // 抛出重载
        }
    } catch (const std::bad_alloc& e) {
        std::cout << e.what() << '\n';
    }
 
    while (true) {
        int* p = new(std::nothrow) int[100000000ul]; // 不抛出重载
        if (p == nullptr) {
            std::cout << "Allocation returned nullptr\n";
            break;
        }
    }
}

输出：

std::bad_alloc
Allocation returned nullptr

参阅

nothrow_t	用于选择不抛出分配函数的标签类型 (类)
operator newoperator new[]	分配函数 (函数)