Incremental variable issue in recursive function

Question

My recursive function is

function recursion($vals,$i) //
{
$htm=implode('',file($vals));
echo $i;
if($htm)
{
return $htm;
}
else
{
    echo "\n.................link broken...................\n";
    sleep(10);
    echo "\n.................retrying......................\n";     
    **// return recursion($vals,$i+1);  //case 1
            // return recursion($vals,$i++);    //case 2**
}
}

using case 1 is incrementing value of $i+1 while using $i++ not increamenting $i value why ?

Passerby · Accepted Answer · 2013-02-06 10:51:49Z

2

Because post-increment ($a++) operator means

Returns $a, then increments $a by one.

Check out official document.

Addition:

And (as @Matt states) pre-increment operator (++$a) means increment and then return.

So in your case, you used

recursion($i++);

Which results in $i returning its current value into function call's parameter, and then increment itself by one, so recursion() will always get the same $i because it is incremented after it is used as a parameter.

Change to

recursion(++$i);

Would help.

edited Feb 6, 2013 at 10:51

answered Feb 6, 2013 at 10:36

Passerby

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1 Comment

Matt Over a year ago

And the pre-increment operator (++$a) means increment by one and then return.

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