php code to validate alphanumeric string
Try this
// Validate alphanumeric
if (preg_match('/^[a-zA-Z]+[a-zA-Z0-9._]+$/', $input)) {
// Valid
} else {
// Invalid
}
Code:
if(preg_match('/[^a-z_\-0-9]/i', $string))
{
echo "not valid string";
}
Explanation:
- [] => character class definition
- ^ => negate the class
- a-z => chars from 'a' to 'z'
- _ => underscore
- - => hyphen '-' (You need to escape it)
- 0-9 => numbers (from zero to nine)
The 'i' modifier at the end of the regex is for 'case-insensitive' if you don't put that you will need to add the upper case characters in the code before by doing A-Z
Use ctype_alnum
like below:
if(ctype_alnum($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