如何使用 new 运算符检查内存分配失败?

How to check memory allocation failures with new operator?(如何使用 new 运算符检查内存分配失败?)

问题描述

就在最近，我将项目的语言从 C 切换为使用 C++.对于 C，我使用了 malloc，然后我检查 malloc 是否成功，但是对于 C++，我使用new"来分配内存，我想知道您通常如何检查内存分配失败.

Just recently I switched the language of my project to use C++ from C. With C, I used malloc and after that I check if malloc was successful but with C++, I use 'new' to allocate memory and I would like to know how you would normally check the memory allocation failure.

从我的谷歌搜索中，我没有看到如下所示.

From my google search, I saw nothrow like the following.

char *buf = new (nothrow)char[10];

我还看到了以下内容.

try{} catch(bad_alloc&) {}

但是接下来呢?我正在使用一些 chrome 库例程来使用智能指针.

But what about the following? I am using some of chrome library routines to use smart pointers.

例如，我的代码如下.

scoped_array<char> buf(new char[MAX_BUF]);

使用智能指针很棒，但我不确定应该如何检查内存分配是否成功.我需要用 nothrow 或 try/catch 分成两个单独的语句吗?您通常如何在 C++ 中进行这些检查?

It is great to use smart pointers but I am just not sure how I should check if the memory allocation was successful. Do I need to break into two separate statement with nothrow or try/catch? How do you normally do these checks in C++?

任何建议将不胜感激.

推荐答案

好吧，你调用 new 会抛出 bad_alloc，所以你必须抓住它:

Well, you call new that throws bad_alloc, so you must catch it:

try
{
    scoped_array<char> buf(new char[MAX_BUF]);
    ...
}
catch(std::bad_alloc&) 
{
    ...
}

或

scoped_array<char> buf(new(nothrow) char[MAX_BUF]);
if(!buf)
{
   //allocation failed
}

<小时>

我的回答是指智能指针传播异常.因此，如果您使用普通的 throw new 分配内存，则必须捕获异常.如果您使用 nothrow new 进行分配，那么您必须检查 nullptr.无论如何，智能指针不会为这个逻辑添加任何东西

---

What I mean by my answer is that smart pointers propagate exceptions. So if you're allocating memory with ordinary throwing new, you must catch an exception. If you're allocating with a nothrow new, then you must check for nullptr. In any case, smart pointers don't add anything to this logic

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