How can one check if a string only contains the characters a-z, A-Z, and 0-9 in PHP?

To check if a string only contains the characters a-z, A-Z, and 0-9 in PHP, you can use a regular expression pattern matching. You can use the preg_match function to check if the string matches the pattern that allows only these characters. If the string contains any other characters, the preg_match function will return false. 

$string = "abc123DEF";
if (preg_match('/^[a-zA-Z0-9]+$/', $string)) {
    echo "String contains only a-z, A-Z, and 0-9 characters.";
} else {
    echo "String contains other characters.";
}

Keywords

PHP string validation regular expression character validation

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