允许字符的正则表达式

Question

i need to check, if the string in my PHP code contains only a specified list of characters. But as some of them might need scape, i just can't get it to work. I have tried everything, but it just doesen't work...

The required validation is:

• 0-9
• AZ
• az
• chars: .%^& ()$#@!/ -+/

Basicaly, i want to check if there is an unknown ascii character (i don't know if there is a function to do that already).

My code is like this now:

if(preg_match("/[A-Za-z0-9\.\#\-\+\*\\\/\=\_\%\$\(\)]/", $cmd) === false)

So, all of the chars are special?

Answer 1

No, all of those characters are not special. If you're unsure, you can let PHP do the escaping for you with preg_quote() :

$regex = '/[A-Za-z0-9' . preg_quote( '.%^&()$#@!/-+/', '/') . ']+/';
if( !preg_match( $regex, $cmd))

Also, preg_match() returns an int , and you're doing === on a boolean, which will never hold true, since they will never be of the same type. You can simply check for if( !preg_match()) .

Answer 2

You might be missing a * at the end of the regexp. Also you could instead have the set expressed like [\\x00-\\x7F] (taken from here ).

This should work:

[\x00-\x7F]*

Answer 3

if(preg_match("/[.%^&()$#@!/+-a-zA-Z\\d\\s]+/", $cmd) === false)并且是否需要锚if(preg_match("/^[.%^&()$#@!/+-a-zA-Z\\d\\s]+$/", $cmd) === false)