most concise way to validate a string

I was wondering what the most concise way to see

if this string is not null or not 8 characters long or not numbers do this

I am just not sure how to put all of those conditions together

 

Regular expression.

if (!preg_match('/^\d{8}$/', $string))
{
    // Invalid string
}

PHP:

 

that seems to be the talk of the day these days.....

would that also check for spaces

for instance i was gonna use

strlen to check for how many characters


say it was an 8 number string

12345678

if i use strlen then they could still enter

12345 78 and it would pass

 

strlen() returns the length of the string. A space is counted as character, so 12345 78 would be an 8 character long string.

 

yes , but preg match woudln't do this?

 

With the right pattern, it won't. I didn't test my code above my I'm pretty confident that it works like it's supposed to.

 

nico_swd's regular expression answer fits your requirement of "most concise" in the original post.

If you are looking for a non regular expression answer you can convert the string to an integer and then if it is less than 10000000 or more than 99999999 it is invalid. Otherwise, valid.

<?PHP

$string = '12345678';
$number = intval($string);

echo "$string => $number => "; 

if ($number < 10000000 || $number > 99999999) {
	echo 'invalid';
} else {
	echo 'valid';
}

?>

PHP:

 

is there an advantage/disadvantage to using a regular expression here

 

Less code would be the obvious one.