为什么try？catch块需要大括号？

问题描述

而在其他语句如if ... else你可以避免大括号，如果只有一个块中的一条指令，你不能这样用try ... catch块：编译器不买它。例如：

While in other statements like if ... else you can avoid braces if there is only one instruction in a block, you cannot do that with try ... catch blocks: the compiler doesn't buy it. For instance:

try
    do_something_risky();
catch (...)
    std::cerr << "Blast!" << std::endl;

使用上面的代码，g ++简单地说，它希望在do_something_risky为什么try ... catch之间的行为差​​异，如果... else？

With the code above, g++ simply says it expects a '{' before do_something_risky(). Why this difference of behavior between try ... catch and, say, if ... else ?

谢谢！

推荐答案

直接使用C ++规范：

Straight from the C++ spec:

try-block:
    try compound-statement handler-seq

正如你所看到的，所有 try -block 需要一个复合语句。根据定义，复合语句是用大括号括起来的多个语句。

As you can see, all try-blocks expect a compound-statement. By definition a compound statement is multiple statements wrapped in braces.

复合语句中的所有内容都确保为try块生成一个新作用域。

Have everything in a compound-statement ensures that a new scope is generated for the try-block. It also makes everything slightly easier to read in my opinion.

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