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

问题描述

刚刚我把我的项目的语言切换到使用C的C ++。
使用C，我使用malloc，然后检查malloc是否成功，但是使用C ++，我使用'new'分配内存和我想知道如何通常检查内存分配失败。

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google搜索，我看到不喜欢以下。

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

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

我也看到了以下内容。

try{} catch(bad_alloc&) {}

关于以下？我使用一些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]);

使用智能指针是很好的，但我只是不知道如何检查内存分配那是成功的。
我需要用nothrow或try / catch分成两个单独的语句吗？
如何通常在C ++中执行这些检查？

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++?

任何建议都将被感激。

推荐答案

好吧，你调用new会抛出 bad_alloc ，所以你必须赶上：

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
}

b $ b

---

我的回答是什么意思是智能指针传播异常。所以如果你用普通的throwing new分配内存，你必须捕获异常。如果你分配一个nothrow新，你必须检查 nullptr 。在任何情况下，智能指针不会添加任何东西到这个逻辑

---

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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