What is the correct/standard syntax for preg_match regular expressions

Question

I keep seeing variations with the delimiters of a preg_match including:

• preg_match("/[xxx]/",$foo)
• preg_match("/^[xxx]$/",$foo)

• preg_match("#[xxx]#e",$foo)

  etc.

Why the variations and which one should be used?

Answer 1

They are all correct.

A delimiter (what you said is open/close tags) can be any non-alphanumeric, non-backslash, non-whitespace character. Ref.