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PHP - preg_match ()

Ok, so I want the user to be able to enter every character from AZ and every number from 0-9, but I don't want them to enter "special characters".

Code:

if (preg_match("/^[a-zA-Z0-9]$/", $user_name)) {
    #Stuff
}

How is it possible to check all provided characters and then check if they were matched? I tried preg_match_all()

it but I didn't really understand it.

As if the user entered "FaiL65Mal", I want him to allow it and go. But if they come in "Fail {] ^ 7 (," I want it to appear with an error.

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3 answers


You just need a quantifier in your regex:

Zero or more characters *

:

/^[a-zA-Z0-9]*$/


One or more characters +

:

/^[a-zA-Z0-9]+$/

Your regex as it is will match a string with only one character, which is either a letter or a number. You want one of the above options to be zero or more, or one or more, depending on whether you want to allow or reject the empty string.

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Your regex should be changed to

/^[a-zA-Z0-9]{1,8}$/


For usernames from 1 to 8 characters. Just tune 8 to the appropriate number and possibly 1.

Your expression currently matches one character

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Please keep in mind preg_match()

that preg_match()

other functions preg_*()

are not reliable 0

either because they return or false

on failure, so a simple if will not throw an error.

Consider using T-Regx :

if (pattern(('^[a-zA-Z0-9]{1,8}$')->matches($input)) 
{
    // Matches! :)
}
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