Question

I have came across the following code, and being a C beginner, I came here for your help.

This function is from a c implmentation of a queue.

Bool queuePut(Queue *q, char c) 
{
    void beep();

    if (queueFull(q)) 
    {
        beep();
        return false;
    }

    //do stuff

    return true;
}

So, I am getting a strange error with gcc on the void beep(). Can someone please explain me what is this, declaring a function inside a function. Or is it the void beep() simply out of place? I was given this code and there’s always the possibility that it isn’t correct.

Edit: The error I am getting:

c:/djgpp/tmp/src/ccrjtmBh.o:queue.c:(.text+0x50): undefined reference to
    '_beep'
collect 2: ld returned 1 exit status.

Is this a linking error?

Answer 1

Most probably you are having a linking error because:

void beep();

is a prototype of a function that has to be defined elsewhere. In C you can’t define a function inside another one. Please, elaborate on the error you are getting.