函数期望在C中返回值

Question

I'm a newbie at C, I am working on someone else's code and I am trying to get rid of a warning that looks like this:

warning: function expects to return value: myfunc

myfunc is declared like this, (I believe it defaults to int)

myfunc(int id, int age) {

   ...
   return;

}

So I try to put void behind myfunc so that it looks like this

void myfunc(int num, int age) {

I get an error:

identifier redeclared: myfunc

  current : function() returning void previous: function() returning int : "students.c", line 233 

But when I go to line 233 of students.c, this is just the first place that I actually call the function. Why is this happening?

I know I could change return to return 0; and then define myfunc as int. But when this function is called, it's not assigned to anything, it's just executed like myfunc(current_id, age); (not int i = myfunc(... for example).

In a situation like this, would it best not to use void? Is it ok to use return; in a void function?

Thanks!

Answer 1

The function myfunc() is declared with no return type (somewhere):

myfunc(int id, int age);

or there is no declaration at all, so it defaults to an int return type. When you specify void at the definition:

void myfunc(int id, int age)
{
}

it does not match the declaration. Change, or add, the declaration:

void myfunc(int id, int age);

You don't need to explicitly write return; in a function with a void return type, but you can if you wish.

Answer 2

You did the right thing by adding void to that implementation of myfunc . However, it looks like the original programmer was sloppy and didn't declare a function prototype for myfunc before using it in students.c . Add that prototype somewhere before line 233 and you should be good to go!