function inside the declaration of a loop?

Question

take this example:

foreach(explode(' ','word1 word2 word3') as $v)
 echo $v;

From what I know php doens't execute every time the explode function, but it will be executed only the first time.

Is this true? And is this true even for user-defined functions?

Is that code better than this or it's equal?

$genericVar = explode(' ','word1 word2 word3');
foreach($genericVar as $v)
 echo $v;

thanks

Answer 1

When using foreach, the two pieces of code are equivalent. The function explode will only be called once.

However, this is not how it works with for loops, for example :

for($i = 0; $i < count($array); ++$i) {}

In this example, the count function will be called at each iteration.

Answer 2

foreach uses a copy of the given array, so the function will be executed only once.

foreach(explodecount(' ','A B C') as $v)
   echo $v;

function explodecount($a,$b){
    echo '@';
    return explode($a,$b);
}

// output: @ABC
// not @A@B@C

but this wont work:

foreach(explode(' ','A B C') as &$v)
   echo $v;

Here you have to store the exploded array in a separate variable.

Answer 3

The separate code is better because it improves readability and maintaining the code will be easier.

Never stuff statements into each other just to remove some lines and make it look compact. Sure, you will be able to save some bytes, but those bytes will bite you later while maintaining it.