1 question anyone

Hi me again, I have a rather puzzling questonsthat none of my books help me with..

take this code: this is not my code i am working on its an examole to explain better!

Code:

#include <iostream>

using namespace std;

void IamAfunction();

int main()
{
IamAfunction();
return 0;
}

void IamAfunction()
{
// code here //
return;
}

Ok, I know you cannot return 0 to a voided function, but why does my compiler allow me to just put return with no number after it? Is it old C type synax? I am also unaware if it will have any cascading effects on the rest of my program.,,,,,

any help would be appreiciated thanks!

return simply implies that you wish for control to be returned to the caller of that function.

a void simply means that the caller shouldn't expect any value to come out of the function, but until that function finishes, or until a return is called, that function holds control over program flow.

You can use return; without any value because you might want to stop function execution and return control back to the main function or what not, if a certain condition was met.

Code:

void function1()
{
   int a;
   cin>>a;
   if(a<0)
   {
     return;//If the person puts in a negetive value, stop the function
                //and return control to the caller.
   }
   cout<<"Your Input was Positive!, your input was: "<<a<<endl;
}

int main()
{
  function1();
  return 0;
}

In this example function1 takes some input from cin, if its less than 0 *a negative number* then it stops program execution and returns control to the caller, which in this case is the main function.

The return call on main (return 0;) returns control to the operating system, with a return value of 0, (Windows doesn't use this, but linux/unix does).

But in essence just think of a call to return as a break on function execution where control is given back to whatever called the function in the first place.

EDIT: Wasn't sure if this even really answered your question, so i will add one more thing.

returns can be called at any point during a functions execution.

Code:

int add(int a, int b)
{
  if((a+b)<0)
   {
     return 0;//We won't allow negative numbers here!
   }
  if((a+b)>100)
  {
    return 100;// Anything larger than 100 we will trunicate
  }
   return (a+b);
 }

So as you can see return values can be put in anywhere, you can even return operations or extra function calls. Hope this helps you to understand returns a little better.