c++ - 为什么 `catch` 在这里 catch ？

Question

我不确定这里发生了什么。很明显为什么内扣会捕获throw 2 ，但为什么外面catch(int x)捕获 throw ?我以为catch(int x)应该只捕获整数值。第二个throw有可能吗？抛出什么是第一次咳嗽(这是 2)？

try
{
    try
    {
        throw 2;
    }
    catch (int n)
    {
        std::cout << "Inner Catch " << n << std::endl;
        throw;
    }
}
catch (int x)
{
    std::cout << "Outer Catch " << x << std::endl;
}

谢谢!

Answer 1

你不能throw没有。 throw;可以在 catch 块中单独使用来重新抛出当前处理的异常。来自 cppreference :

Rethrows the currently handled exception. Abandons the execution ofthe current catch block and passes control to the next matchingexception handler (but not to another catch clause after the same tryblock: its compound-statement is considered to have been 'exited'),reusing the existing exception object: no new objects are made. Thisform is only allowed when an exception is presently being handled (itcalls std::terminate if used otherwise). The catch clause associatedwith a function-try-block must exit via rethrowing if used on aconstructor.

I thought catch(int x) is supposed to catch integer values only

这就是它的作用。

Is it possible that the second throw throws what was first cought (which is 2)?

正是这样。