regex to check the string contains only letter and numbers but not only numbers

Question

I need a help with regex which checks the string contains only letter and numbers but not only numbers

Valid

* letters
* 1wret
* 0123chars
* chars0123
*          


        

Answer 1

^[0-9]*[a-zA-Z]+[0-9a-zA-Z]*$

translated: from the beginning, match 0 or more numbers, then match at least one letter, then match zero or more letters or numbers until the end.

Answer 2

Here are the components of the regex we're going to use:

• ^ and $ are the beginning and end of the string anchors respectively
• \d matches a digit
• [a-zA-Z] matches a letter
• [a-zA-Z\d] matches a letter or a digit
• * is "zero-or-more" repetition

With these, we can now compose the regex we need (see on rubular.com):

^\d*[a-zA-Z][a-zA-Z\d]*$

Here's an explanation of the pattern:

from the beginning...  till the end
|                      |
^\d*[a-zA-Z][a-zA-Z\d]*$
 \_/\______/\_________/

The 3 parts are:

• Maybe some digits as a prefix...
• But then definitely a letter!
• And then maybe some digits and letters as a suffix

References

• regular-expressions.info/Character Class, Anchors, and Repetition

Answer 3

Instead of using a regular expression, you can also use the ctype_*() functions:

var_dump(ctype_alnum('letters') && !ctype_digit('letters'));     // bool(true)
var_dump(ctype_alnum('0123chars') && !ctype_digit('0123chars')); // bool(true)
var_dump(ctype_alnum('1324') && !ctype_digit('1324'));           // bool(false)
var_dump(ctype_alnum('xcvxxc%$#') && !ctype_digit('xcvxxc%$#')); // bool(false)

But if you want a regular expression, you can use this:

var_dump(preg_match('/^[a-z0-9]*[a-z]+[a-z0-9]*$/i', $input));

Answer 4

This should do it:

^[0-9]*[a-zA-Z]+[a-zA-Z0-9]*$

This requires at least one character of [a-zA-Z].

Answer 5

[a-z0-9]*[a-z]+[a-z0-9]*

Answer 6

^(?=.*[a-z])[a-zA-Z0-9]+$

• (?=.*[a-z]) positive lookahead to make sure that there is at least one letter in the string (but doesn't consume any characters - gives up the matched characters as soon as it returns (in this case, as soon as it finds a letter)).
• [a-zA-Z0-9]+ make sure string contains only alphanumeric characters.
• ^ and $ are start and end of string delimiters.