Regexp to match everything "except these"

Question

I am wanting to sanitize a user input string in PHP using preg_replace() and the sanitized string should only be allowed to have plus or minus characters in it.
I thought this would be a rather simple thing to do with regex, but I'm struggling to find some thing that will catch all the special characters (except for - and +)

\w is a word and catches all chars Aa-Zz and 0-9 i think.
\W is any non-word character so that will also catch + and - chars.

Is there a regex to say \w and (\W excepting + OR -) ?

Answer 1

you want your sanitized string to only contain + or - ?
"everything except" could be simplified to simply except.
As Orin Cook said, you need to use ^ for negation.
Modifying Snehil 's code, you get:

$sanitized_string = preg_replace('/[^\+\-]/', '', $string);

where every character in $string except '+' or '-' gets selected and replaced with '', leaving only + or -.

Like Thanos snapping his fingers😁.

Answer 2

^ is the regex symbol for "not", so eg ^\w matches anything other than alphanumerics.

Unfortunately, it's also the symbol for "starts with" if you put it at the beginning of your expression, so be careful with that.

Answer 3

Do you mean keep every special character except + & -?
https://code.sololearn.com/w2LYKVPFUIoI/?ref=app

Answer 4

<?php echo
" <script>
alert('Bob_Li, its could be JS also😂');
</script> ";
?>

Answer 5

You don't need regex for so simple task, ..
make some filter.
ASCII code 43(+) 45(-)..
only these symbols...
if( '+' || '-') ok...
Something like that...

Answer 6

Smith Welder
agreed, it can be solved without regex.
But..
expand("Something like that...")😁

Answer 7

Bob_Li
Its got it ✅, so expand can be is over xd

Answer 8

Smith Welder
Non regex solutions
(sorry for the response overload, but topics like these motivate me to brush up my very dusty php..😅)

foreach(str_split($string) as $c)
if($c=="+"||$c=="-")
echo $c;

or if you must use a variable

$sanitized_str ='';
foreach(str_split($string) as $c)
if($c=="+"||$c=="-")
$sanitized_str .= $c;
echo $sanitized_str;

or
foreach(str_split($string) as $c)
if(in_array($c,array("+","-"),TRUE))
echo $c;

Answer 9

Bob_Li
shake off the dust from php, get time to use that.. 😂