Regular Expression match lines starting with a certain character OR whitespace and then that character

Question

I am trying to write a regular expression that matches lines beginning with a hyphen (-) OR that begins with spaces or tabs and then has a hyphen. So it should match the followi

Answer 1

You can try

^\s*-

• ^: start of string
• \s*: zero or more whitespace characters
• -: a literal - (you don't need to escape this outside a character class)

Answer 2

the above (using \s*) is the easiest one for this case, but in general, you can always use the | syntax:

re.match('^-|^\s+-', '- hello')
<_sre.SRE_Match object at 0x0000000054E72030>

re.match('^-|^\s+-', '     - hello')
<_sre.SRE_Match object at 0x0000000054E72030>

re.match('^-|^\s+-', '     + hello')
None

^- is the case for - at beginning, `^\s+-' is with one or more spaces, and | chooses either one.

Answer 3

You can use this regex by making 0 or more spaces optional match at beginning:

^\s*-