PHP - regex to allow letters and numbers only
PhpRegexPreg MatchPhp Problem Overview
I have tried:
preg_match("/^[a-zA-Z0-9]", $value)
but im doing something wrong i guess.
Php Solutions
Solution 1 - Php
- Use PHP's inbuilt ctype_alnum --
You dont need to use a regex for this, PHP has an inbuilt function ctype_alnum which will do this for you, and execute faster:
<?php
$strings = array('AbCd1zyZ9', 'foo!#$bar');
foreach ($strings as $testcase) {
if (ctype_alnum($testcase)) {
echo "The string $testcase consists of all letters or digits.\n";
} else {
echo "The string $testcase does not consist of all letters or digits.\n";
}
}
?>
2. Alternatively, use a regex
If you desperately want to use a regex, you have a few options.
Firstly:
preg_match('/^[\w]+$/', $string);
\w includes more than alphanumeric (it includes underscore), but includes all
of \d.
Alternatively:
/^[a-zA-Z\d]+$/
Or even just:
/^[^\W_]+$/
Solution 2 - Php
You left off the / (pattern delimiter) and $ (match end string).
preg_match("/^[a-zA-Z0-9]+$/", $value)
Solution 3 - Php
- Missing end anchor $
- Missing multiplier
- Missing end delimiter
So it should fail anyway, but if it may work, it matches against just one digit at the beginning of the string.
/^[a-z0-9]+$/i
Solution 4 - Php
As the OP said that he wants letters and numbers ONLY (no underscore!), one more way to have this in php regex is to use posix expressions:
/^[[:alnum:]]+$/
Note: This will not work in Java, JavaScript, Python, Ruby, .NET
Solution 5 - Php
try this way .eregi("[^A-Za-z0-9.]", $value)