CODEWITHSUNDEEP
phpregexpreg-match
Cesar
Cesar

Reputation: 4136

preg_match match a defined number of characters requiring at least one digit and at least one letter

I need a regex to extract a code_number, the requirements are:

Ideally this should be done using only one regex.

With the following regex I'm almost there, the problem is that this regex does not comply whit the third requirement, it should not match the 11111 because the lack of at least one letter

$regex = '~\b(?=[a-zA-Z0-9]{5}\b)[a-zA-Z0-9]*\d[a-zA-Z0-9]*~';
$sms = ' 11111 keyrod  07:30 02.10.2013';

preg_match($regex, $sms, $matches);

print_r($matches); // print array([0] => 11111)

How could I change this regex to not match a string of only number?

Upvotes: 2

Views: 5281

Answers (2)

Casimir et Hippolyte
Casimir et Hippolyte

Reputation: 89639

try this:

$subject = ' :::5: abcde4 abcd4 12345 abcde :a:1:';

$regex = '~(?<= |^)(?=\S{0,4}\d)(?=\S{0,4}[a-z])\S{5}(?= |$)~i';

preg_match_all($regex, $subject, $matches);

print_r($matches);

explanation:

(?<=) and (?=) are respectively a lookbehind and a lookahead assertions. They test a condition before or after and don't eat any characters. (They are zero width)

In this case:

(?<= |^)  --> a space or the beginning of the string before
(?= |$)   --> a space or the end of the string after

The character class:

\S  --> all characters that are not white (space, tab, newline..)

The conditions:

At least one digit is forced by the lookahead:

(?=\S{0,4}\d) there's between 0 and 4 non-blank characters and a digit. In other words you can have:

1
x1
xx1
xxx1
xxxx1

it's the same for the letters with (?=\S{0,4}[a-z])

The number of characters for the string is forced with \S{5} and the first and final lookaround that forbid all non-white characters before and after.

Upvotes: 1

Jonathan Kuhn
Jonathan Kuhn

Reputation: 15311

Based on the rules you describe, nothing in your $sms string will match. But based on those rules, try this:

preg_match('~\b(?=[a-z0-9]{0,4}[a-z])(?=[a-z0-9]{0,4}[0-9])[a-z0-9]{5}\b~i', $subject, $matches);

Using your example string and Casimir's example string: http://codepad.viper-7.com/NA2mI5

Output:

//Your example string:
Array
(
)

//Other sample string:
Array
(
    [0] => abcd4
)

Upvotes: 2

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