How to optimize multiple !$vars in submit ?

4rxsid

Hi all,
How could I optimize this server side check for missing form data?

if(!$varA || !$varB || !$varC || !$varD || !$varF || !$varG) {
   //some error for missing form data
}

Can the var's to check be put in some kind of array?

thanks...

128kb_com

I wrote this neat little function to do just that a while back, I use it all the time, it goes like:

function chkReqFields( $field_array, $flag = 'ALL' )
{
	for ($i = 0; $i < sizeof($field_array); $i++) {
		if ($_POST[$field_array[$i]] && $flag == 'ONE_EXHISTS') 
			return 1;
		if (!$_POST[$field_array[$i]] && $flag == 'ALL')
			return 0;
	}
	if ( $flag == 'ONE_EXHISTS' )
		return 0;
	else
		return 1;
}

as you can see, it has an optional parameter so you can check if all the required fields are set or if one is missing.

I use it like:

if (chkReqFields($required_fields, 'ONE_EXHISTS')) {
	if (chkReqFields($required_fields)) {
		echo "all fields are set...";
	} else {
		echo "all fields are not set";
} else {
	echo "No fields are set";
}

just create an array with the names of the required fields add pass it to the function. This works well for a few different situations...

4rxsid

thanks for the reply 128...but is that really more efficient?

diego25

What do you mean by "more efficient"? More efficient during the execution time, or more efficient for the programmer to write?

128kb.com's solution allows the programmer to save some time (so it's more efficient for the programmer), but both your code and his code will take about the same time to execute (it's not more efficient for PHP).

Diego

4rxsid

perhaps i thought it would be implied to be a question of which is more efficient for the server...to serve it up, since the programmer would only write it once (baring any changes), but would be served potentially numerous times daily. especially since just looking at 128's code & my code reveals fewer keystrokes needed for mine.

but i do thank everyone for their reply's!

cheers...

diego25

Well, if you search this board, you'll find that someone recently did a benchmark comparing if statements and switch statements. You'll see that many (I forgot how many he did) if statements take only in the tens of milliseconds...so I don't think something like
if(!$varA || !$varB || !$varC || !$varD || !$varF || !$varG) {
could be sped up any more. Besides, I can't think of any possible way of speeding up that if statement because of its simplicity. The only way I know of would involve changing the processor type to a vector processor. But even if you did, the speed of execution for that if statement wouldn't change dramatically.

Diego

128kb_com

I agree with diego25,

The runtime of chkReqFields/COLOR; is On where n is equal to how many values are in $required_fields, so its not that bad, but when you have 20 POST fields to check your gonna have one very long if(POST || POST || ....

I don't know which is worse....

4rxsid

hmmm...

what about doing something like this:

if(!($varA && $varB && $varC && $varD && $varF && $varG)) {
//some error for missing form data
}

would that fail only if EACH of those vars is not set?

128kb_com

Yeah, using the && operator will check for truth on BOTH sides of the && or return false. It should have the same runtime compexity of the mulitple ||'s.

The thing about the function I posted earlier is, it will function either way you want to use it (eg. in the POST && POST.. case or the POST || POST .. case). Thats what makes it effiecient for me. If you need to display the apporpriate error for forms missing only one field or missing all fields it will work.

Either that or you can have multiple &&'s and multiple ||'s right next to each other for every form var, ugly!. On the other hand, you can have your functions include/COLOR 'd and minimize code down to a minimum.

Is a couple of miliseconds (if that) that important to you?