php code to validate alphanumeric string

Question

I want to validate alphanumeric string in form text box in php. It can contain numbers and special characters like '.' and '-' but the string should not contain only numbers and special characters. Please help with the code.

Answer 1

Use ctype_alnum like below:

if(ctype_alnum($string)){
    echo "Yes, It's an alphanumeric string/text";
}
else{
    echo "No, It's not an alphanumeric string/text";
}

Read function specification on php.net

Answer 2

Try this

// Validate alphanumeric
if (preg_match('/^[a-zA-Z]+[a-zA-Z0-9._]+$/', $input)) {
    // Valid
} else {
    // Invalid
}