Question

I am using python, and this regexp doesn’t match, and I don’t understand why.

string = "15++12"
if re.match("[-+*/][-+*/]+",string):
    # raise an error here

I am trying to raise an error, if one or more of “-“,”+”,”*”,”/” follows another one of those.

Answer 1

Use re.search() as re.match() only searches at the beginning of the string:

string = "15++12"
if re.search("[-+*/][-+*/]+",string):
    # raise an error here

Also, this could be simplified to:

string = "15++12"
if re.search("[-+*/]{2,}",string):
    # raise an error here

as the {2,} operator searches for two or more of the previous class.