C++ catch 块 - 按值或引用捕获异常? [英] C++ catch blocks - catch exception by value or reference?

问题描述

可能的重复:
在 C++ 中通过指针捕获异常

我总是按值捕获异常.例如

I always catch exceptions by value. e.g

try{
...
}
catch(CustomException e){
...
}

但我遇到了一些用 catch(CustomException &e) 代替的代码.这是 a) 好的 b) 错误的 c) 灰色区域吗?

But I came across some code that instead had catch(CustomException &e) instead. Is this a)fine b)wrong c)a grey area?

推荐答案

C++ 中异常的标准做法是......

The standard practice for exceptions in C++ is ...

按值抛出，按引用捕获

在继承层次结构面前，按值捕获是有问题的.假设对于您的示例，还有另一种类型 MyException 继承自 CustomException 并覆盖错误代码等项目.如果抛出 MyException 类型，您的 catch 块将导致它被转换为一个 CustomException 实例，这将导致错误代码发生变化.

Catching by value is problematic in the face of inheritance hierarchies. Suppose for your example that there is another type MyException which inherits from CustomException and overrides items like an error code. If a MyException type was thrown your catch block would cause it to be converted to a CustomException instance which would cause the error code to change.

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