什么时候是一个函数try块有用？ [英] When is a function try block useful?

问题描述

我想知道程序员何时使用函数try块。何时有用？

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

编辑：由于一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）说没有它不正确。它被称为function-try-block。参见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

从初始化。通常，你不会捕获那些错误，所以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 (...) { ... }

完全等同于

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

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