Regular expression to find two strings anywhere in input

Question

How do I write a regular expression to match two given strings, at any position in the string?

For example, if I am searching for cat and mat

Answer 1

If you absolutely need to only use one regex then

/(?=.*?(string1))(?=.*?(string2))/is

i modifier = case-insensitive

.*? Lazy evaluation for any character (matches as few as possible)

?= for Positive LookAhead it has to match somewhere

s modifier = .(period) also accepts line breaks