Allow only [az] [AZ] [0-9] per line using PHP

Question

How can I get a string containing only z to z, A to Z, 0 to 9, and some characters?

Answer 1

You can check your string (let $str ) with preg_match :

 if(preg_match("/^[a-zA-Z0-9]+$/", $str) == 1) { // string only contain the a to z , A to Z, 0 to 9 } 

If you need more characters, you can add them before ]

Answer 2

You can filter it like this:

 $text = preg_replace("/[^a-zA-Z0-9]+/", "", $text); 

As for some characters , you should be bigger

Answer 3

No regular expression needed, you can use Ctype functions:

• ctype_alnum : check alphanumeric characters
• ctype_alpha : check alphabetical character (s)
• ctype_cntrl : check control character (s)
• ctype_digit : check for numeric characters
• ctype_graph : check any printable character (s) except space
• ctype_lower : check lowercase letters
• ctype_print : check for printable characters
• ctype_punct : check for any printable character that is not a space or alphanumeric character.
• ctype_space : check whitespace character (s)
• ctype_upper : check uppercase characters
• ctype_xdigit : check character (s) representing a hexadecimal digit

In your case, use ctype_alnum , for example:

 if (ctype_alnum($str)) { //... } 

Example:

 <?php $strings = array('AbCd1zyZ9', 'foo!#$bar'); foreach ($strings as $testcase) { if (ctype_alnum($testcase)) { echo 'The string ', $testcase, ' consists of all letters or digits.'; } else { echo 'The string ', $testcase, ' don\'t consists of all letters or digits.'; } } 

Online example: https://ideone.com/BYN2Gn

Answer 4

Why are these “symbols” there in the first place? It looks like you are reading text from a source that is encoded as UTF-16, but you are decoding it as something else, like latin1 or ASCII.

Answer 5

Both of these regular expressions should do this:

 $str = preg_replace('~[^a-z0-9]+~i', '', $str); 

Or:

 $str = preg_replace('~[^a-zA-Z0-9]+~', '', $str); 

Answer 6

The best and most flexible way to achieve this is by using regular expressions. But I'm not sure how to do this in PHP, but this article may help. link

Answer 7

The shortcut will look like this:

 if (preg_match('/^[\w\.]+$/', $str)) { echo 'Str is valid and allowed'; } else echo 'Str is invalid'; 

Here:

 // string only contain the a to z , A to Z, 0 to 9 and _ (underscore) \w - matches [a-zA-Z0-9_]+ 

Hope this helps!