如何抛出C ++异常 [英] How to throw a C++ exception

问题描述

我对异常处理有很差的理解（例如，如何为我自己的目的定制throw，try，catch语句）。

定义一个函数如下： int compare（int a，int b）{...}

< d当函数a或b为负时，函数会抛出一个异常。

我应该如何在函数定义中处理这个问题？

解决方案

简单：

  #include< stdexcept> 
 
 int compare（int a，int b）{
 if（a< 0 || b< 0）{
 throw std :: invalid_argument ）; 
} 
} 
  

标准库提供了一个漂亮的内置异常对象。请记住，您应该始终按值引用并按引用捕获：

 尝试{
 compare（-1， 3）; 
} 
 catch（const std :: invalid_argument& e）{
 // do stuff with exception ... 
} 
  

每次尝试后可以有多个catch（）语句，因此如果需要，您可以单独处理不同的异常类型。

您还可以重新抛出异常：

  catch std :: invalid_argument& e）{
 //做某事
 
 //让某人更高的调用堆栈处理它，如果他们想要
 throw e; 
} 
  

并且捕获异常，无论类型如何：

  catch（...）{}; 
  

I have a very poor understanding of exception handling(i.e., how to customize throw, try, catch statements for my own purposes).

For example, I have defined a function as follows: int compare(int a, int b){...}

I'd like the function to throw an exception with some message when either a or b is negative.

How should I approach this in the definition of the function?

解决方案

Simple:

#include <stdexcept>

int compare( int a, int b ) {
    if ( a < 0 || b < 0 ) {
        throw std::invalid_argument( "received negative value" );
    }
}

The Standard Library comes with a nice collection of built-in exception objects you can throw. Keep in mind that you should always throw by value and catch by reference:

try {
    compare( -1, 3 );
}
catch( const std::invalid_argument& e ) {
    // do stuff with exception... 
}

You can have multiple catch() statements after each try, so you can handle different exception types separately if you want.

You can also re-throw exceptions:

catch( const std::invalid_argument& e ) {
    // do something

    // let someone higher up the call stack handle it if they want
    throw e;
}

And to catch exceptions regardless of type:

catch( ... ) { };

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