std::nothrow

 

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函数

operator newoperator new[]

operator deleteoperator delete[]

get_new_handler (C++11)

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类

bad_alloc

bad_array_new_length (C++11)

nothrow_t

align_val_t (C++17)

destroying_delete_t (C++20)

类型

new_handler

对象

nothrow

 

定义于头文件 <new>
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)