Return values in a function

[newladder]

Hello,

I know this is a vauge question, but since iam new to the programming world just wanted to clarrify this silly doubts.

Why do we need return in the function when we can use echo and get the output ?

Can someone explain the basic of funtions ?

Thanks in advance.

[Ize]

Using echo inside a function is very bad practice. It almost always only works for one specific situation and can therefore never be used again in other projects.

Furthermore, splitting up code inside functions (and better: classes) gives you more flexibility in what to do with certain data.

For instance, let's say I've got an array, which I want to print in an HTML ordered list, but only the first 40 characters. This would work:

function makeListFromArray ($array)
{
  echo '<ol>';
  foreach ($array as $a)
  {
    echo '<li>' . substr($a, 0, 40) . '</li>';
  }
  echo '</ol>';
} 

But that's not really flexible, is it? What if I want to print out the entire string in a different situation, should I write another function called "makeListFromArrayComplete()"? Or what if I wanted to print only 30 characters instead of 40, should I write a whole new function?
This is where the real power of functions lies. Instead of really modifying values or printing it out directly, we can divide functionality.
Also, we can save the return value of a function inside a variable and use it later. Remember this: separate responsibilities!

And last but not least; in big applications a function's purpose is almost never to just output something. Most functions I write modify data and return this new data.

[nabil_kadimi]

Some times you need the value returned to give it to another function or to use it in an expression...

function num_is_even($number){
    if( $number & 1 )    return FALSE;
    else return TRUE;
}

$test=15;
 
if(num_is_even($test){
    //things to do if $test is even
}

if(!num_is_even($test){
    //things to do if $test is odd
}