Question

i want the regular expression to sanitize my data which should meet the following condition

a) a-z and A-Z allowed

b) 0-9 allowed

c) Special Symbols like Comma (,) dot (.) question Mark (? allowed)

d) Single Space is allowed

i tried and came up with this

preg_replace('%[^a-zA-Z0-9,.?\s]%', '', $string);

i am not so familiar with RegExp, although the above code works, i would like to know

a) if i am using the correct RegExp
syntax?

b) if i don’t use modulus(%) at the
start and end of the syntax it won’t
work, and i have no idea what is the
purpose of modulus here?

Answer 1

a) If it works, it’s correct.

b) “When using the PCRE functions, it is required that the pattern is enclosed by delimiters. A delimiter can be any non-alphanumeric, non-backslash, non-whitespace character” – from PHP Documentation