1 question anyone

This is a discussion on 1 question anyone within the C++ Programming forums, part of the General Programming Boards category; Hi me again, I have a rather puzzling questonsthat none of my books help me with.. take this code: this ...

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    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!

  2. #2
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    Jun 2005
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    32
    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.
    Last edited by Charmy; 06-24-2005 at 01:28 AM.

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