Question

I want to match a string with a regular expression in C#. The string can only be preceeded by zero or more whitespaces, no other characters is allowed.

Valid strings are:

"> 5", " > 5"

Invalid strings are:

"1 > 5", "1> 3", ">> 3"

I have this regular expression right now:

"\s*> "

I have also tried "[\s*]> " and "[\s]*> " but with no luck.

This seems like a simple problem, but im fresh to regular expressions and i failed to find an answer elsewhere.

Thanks in advance!

Answer 1

I don’t think you simply meant “start with 0 or more whitespace characters”, because then every string would be valid, including the empty string, because it satisfies at least “start with 0 whitespace”.

Looking at your sample input, perhaps you meant “start with 0 or more whitespace characters, followed by exactly one >“. In that case, this regex should do it:

^\s*>[^>]*$

Replace the second * with a + if you need to match stuff after the > sign.