Question

I need to filter user input to only alphanumeri, commas, fullstop and spaces.
I actually tried this code below but other unwanted characters are going through.

if(!preg_match('/^[,. 0-9A-Za-z]/', $input)
{
   echo "invalid";
}

How can i enable the input to strictly accept only these characters stated above?

Answer 1

The negation character (^) needs to go inside of the character class:

if(preg_match('/[^,\. 0-9A-Z]/i', $input))
{
   echo "invalid";
}