PHP validation question - php

Question

How do I check and see if a user enters only numbers and is at least 4 numbers long using PHP?

Answer 1

Mark Byers' suggestion is good, but here's another way:
$valid = ctype_digit($number) && strlen($number) >= 4;

Answer 2

You could use a regular expression:
/^\d{4,}$/
Example usage:
$s = "7325";
if (preg_match('/^\d{4,}$/', $s)) {
echo "matches";
}

Answer 3

ctype_digit() && strlen() wins
<?php
function benchmark($callback){
echo sprintf('%-30s: ', $callback);
$t = microtime(true);
foreach(range(1, 10000) as $n){
call_user_func($callback);
}
echo (microtime(true)-$t)."\n";
}
function mark_byers_preg_match(){
$s = "7325";
preg_match('/^\d{4,}$/', $s);
}
function notjim_ctype_digit_strlen(){
$number = 7325;
ctype_digit($number) && strlen($number) >= 4;
}
function tomalak_intval_broken(){
$check = 7325;
intval($check) == $check && $check >= 1000 && $check <= 9999;
}
benchmark('mark_byers_preg_match');
benchmark('notjim_ctype_digit_strlen');
benchmark('tomalak_intval_broken');
?>
results
mark_byers_preg_match : 0.029040098190308
notjim_ctype_digit_strlen : 0.026585817337036
tomalak_intval_broken : 0.019872903823853
Note: #Tomalak's does not work with numbers starting with 0 so it does not qualify
Edit: #kiethjgrant's solution was removed because intval(0000) evaluates as false when it should be true.

Answer 4

Do you have any example code to start with?
To strictly answer your question, you could use a regex like if(preg_match('/^\d{4,}$/', $input)....
But there's a lot more to consider here: you need to consider both validation and filtering (and you're best to keep the two separate issues). If you're strictly checking for an integer, then I suppose you're safe from SQL injection, XSS, etc., but you really need to have a handle on those issues, because sooner or later you're going to need to filter & validate something other than a simple integer.

Answer 5

you should always use the most efficient way to do it
if ( is_numeric($imput) && isset($input[3]) )
{
// your code
}
isset() is a language construct, which is always faster than strlen().
isset($input[n-1]) tells you whether string(data which passes through form is always string) has at least n long.
is_numeric() checks it is a valid num string.
i think it is better than ctype_digit() && strlen().