c - 功能范围示例

Question

以下是 block 作用域的示例:

int func(int a) {
    int b;     
    ...
              
}             // end of block scope for a & b

什么是函数范围的例子，我认为它适用于 goto 标签？

Answer 1

来自 C 标准，6.2.1 标识符的范围:

A label name is the only kind of identifier that has function scope. It can be used (in a goto statement) anywhere in the function in which it appears, and is declared implicitly by its syntactic appearance (followed by a : and a statement).

它与 block 作用域不同的原因是它忽略了 block :

void f(int a) {
    {
        increase_a: ++a;
    }

    if (a)
        goto increase_a;
}

这可以编译，因为 increase_a 对 goto 语句是可见的，如果它具有 block 范围，则不会出现这种情况。