help with validate field

Question

hello,

how do i check a field contain number and alphabet.

something like $str = 3ab, ab3, a3

Answer 1

To check if a string contains number and alphabet you can do, write a small regex based function as:

function contains_num_alpha($str) {

return preg_match('/^[a-z0-9]+$/i',$str); 

}

The regex used: ^[a-z0-9]+$

• ^, $ - anchors
• [a-z0-9] - char class that matches a single digit or a single alphabet.
• [a-z0-9]+ - one or more digits/alphabets.
• i - to make the matching case insensitive.

If you want to allow even empty string, you can change + to * in the regex.

Answer 2

You can use regex

    $stringGood = 'abc2';

    $stringBad = '2#2(7X%';

    function isValidAlphaNum($str) {

     return preg_match('/^[a-z\d]+$/i', $str);

    }

    var_dump(validateAlphaNum($stringGood)); // true
    var_dump(validateAlphaNum($stringBad)); // false

If you wanted to allow uppercase and lowercase alphabetical characters, numbers and underscore you can use this regex: /^\w+$/

Answer 3

Not sure of what you're asking, but if you want to check whether a string has at least 1 alpha and 1 numeric character in it, then this regular expression ought to do it:

<?php

if (preg_match("^[a-zA-Z0-9]{1,}$", $str) {
  // match was found;
}
?>

Answer 4

<?php
 if (is_string("23")) {
  echo "is string\n";
  } else {
   echo "is not an string\n";
   }
   var_dump(is_string('abc'));
   var_dump(is_string("23"));
   var_dump(is_string(23.5));
   var_dump(is_string(true));
   ?> 

Use the is_string function. Returns TRUE if the argument type is string , FALSE otherwise.

<?php 
$tests = Array(
                "42",
                1337,
                "1e4",
                "not numeric",
                Array(),
                9.1
              );

foreach($tests as $element)
{
        if(is_numeric($element))
        {
                echo "'{$element}' is numeric", PHP_EOL;
        }
        else
        {
                echo "'{$element}' is NOT numeric", PHP_EOL;
        }
}
?>

If you want to check the input is numeric use the "is_numeric" function

It return true, if the argument is numeric. Else it return false