Function scope

 

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Function scope starts with the opening brace ({) of a function and ends with the closing brace (}) of that function.

A label name is the only kind of identifier that has function scope. Using a label name may occur (in a goto statement) anywhere in the function in which the label name appears. The syntactic appearance of a label name, that is a name followed by a colon (:) and a statement, implicitly declares the label name.

So, a label is visible throughout the function in which the label's declaration resides. A goto statement which targets a label must be in the same function as the label's declaration. The goto statement may appear before or after the label that it targets.

Example

Labels and goto's perform a while loop.

Run this code

#include <stdio.h>
 
int main(void)
{   /* start of a function scope */
 
    /* Simulate "while (i<5) { ... }". */
    int i = 0;
    top_of_loop:
    if (!(i<5)) goto label_3;   /* goto appears before label declaration */
        printf("i = %d\n", i);
        ++i;
        goto top_of_loop;       /* goto appears after label declaration  */
 
    label_3:
    return 0;
}   /* end of a function scope */
/* end of this translation unit, end of file scope */

Possible output:

i = 0
i = 1
i = 2
i = 3
i = 4