[Resolved] error checking regular expression

[nobertos]

hi,

i need to check a string, $user_id, that sent from a form to make sure it doesn't contain characters other than letters, numbers, and the underscore _

what is a good way to do this?

check string - somehow
if it passes, return true
if it doesn't, return false

-c

[nobertos]

also, i need to do another error check where i check to make sure the $password has at least 2 numbers in it, i assume that would be easy with the appropriate regular expression

-c

[rpanning]

Below are simple regex that cover your criteria. But, you might want to be more restrictive, like user max length, password minimum length, etc...

 
// One or more; characters (case insensitive), numbers, or _
if (preg_match("/^[a-z0-9_]+$/i", $user_id)) {
    // Good
} else {
    // Bad
}

// At least two numbers, no length limit.
if (preg_match("/[0-9]{2,}/", $password)) {
    // Good
} else {
    // Bad
}

[swr]

rpanning's second example will only allow passwords that have two numbers right together. To allow something like "blah1blah2" you'll need to change this:
"/[0-9]{2,}/"
to this:
"/[0-9].*[0-9]/"

[rpanning]

Originally posted by swr
rpanning's second example will only allow passwords that have two numbers right together. To allow something like "blah1blah2" you'll need to change this:
"/[0-9]{2,}/"
to this:
"/[0-9].*[0-9]/"

My bad. :rolleyes: