CODEWITHSUNDEEP
regexpreg-match
Mark
Mark

Reputation: 89

preg_match allow letters and numbers but at least 1 letter

I have the following preg_match statement that allows an input to be either letters a to z and numbers 0 to 9 only and it must be between 5 and 30 characters in length.

However, how would I also make sure that the input is not all numerics? For example it must contain at least 1 a to z letter?

if (preg_match ('/^[a-zA-Z0-9\'.]{5,30}$/i', $str['user'])) {
}

Upvotes: 2

Views: 767

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626738

You wrote you have a regex that allows an input to be either letters a to z and numbers 0 to 9 only, but actually ^[a-zA-Z0-9\'.]{5,30}$ matches a string of 5 to 30 ASCII letters, digits and also ' or ..

If you just want to make your regex match what it matches, but not a string that only consists of digits, use a (?!\d+$) lookahead:

'/^(?!\d+$)[a-z0-9\'.]{5,30}$/i'
   ^^^^^^^^

Note you do not need to specify the A-Z or a-z range if you use a i case insensitive flag (just either of them is enough).

The (?!\d+$) is a negative lookahead that fails the match if there are one or more digits followed by the end of string ($) immediately to the right of the current location (which is the start of the string).

See the regex demo.

If you do not want to match a string that only consists of dots, or ', or digits, use

'/^(?!(?:\d+|([\'.])\1*)$)[a-z0-9\'.]{5,30}$/i'

See another demo.

Upvotes: 3

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