什么时候函数 try 块有用?

When is a function try block useful?(什么时候函数 try 块有用?)

问题描述

我想知道程序员何时使用函数 try 块.什么时候有用?

I'm wondering when programmers use function try blocks. When is it useful?

void f(int i)
try
{
   if ( i  < 0 ) 
      throw "less than zero";
   std::cout << "greater than zero" << std::endl;
}
catch(const char* e)
{
    std::cout << e << std::endl;
}

int main() {
        f(1);
        f(-1);
        return 0;
}

输出:(在ideone)

greater than zero
less than zero

正如有些人可能认为函数定义的语法不正确(因为语法看起来不熟悉)，我不得不说不，它不正确.它被称为函数尝试块.请参阅 C++ 标准中的 §8.4/1 [dcl.fct.def].

As some people might think that the syntax of function defintion is incorrect (because the syntax doesn't look familiar), I've to say that no its not incorrect. Its called function-try-block. See §8.4/1 [dcl.fct.def] in the C++ Standard.

推荐答案

您可以在构造函数中使用它来捕获初始化程序中的错误.通常，您不会发现这些错误，因此这是一个非常特殊的用途.

You use it in constructors to catch errors from initializers. Usually, you don't catch those errors, so this is a quite exceptional use.

否则，这是无用的:除非我被证明是错误的，

Otherwise, it is useless: unless I'm proven wrong,

void f() try { ... } catch (...) { ... }

严格等同于

void f() { try { ... } catch (...) { ... } }

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