How do I check if the first X characters of a string are numbers? - Printable Version +- Python Forum (https://python-forum.io) +-- Forum: Python Coding (https://python-forum.io/forum-7.html) +--- Forum: General Coding Help (https://python-forum.io/forum-8.html) +--- Thread: How do I check if the first X characters of a string are numbers? (/thread-39762.html) |
How do I check if the first X characters of a string are numbers? - FirstBornAlbratross - Apr-11-2023 How do I check if the first X characters of a string are numbers? For example if someone inputs a combination of numbers and characters, how can I check to see if the first 3 characters are numbers? RE: How do I check if the first X characters of a string are numbers? - menator01 - Apr-11-2023 You could use string splice and isdigit RE: How do I check if the first X characters of a string are numbers? - deanhystad - Apr-11-2023 Or a regular expression. https://docs.python.org/3/library/re.html import re for string in ('123ab', '12.3ab', '12', '123', 'a123'): print(string, re.match(r'\d{3}.*', string))
RE: How do I check if the first X characters of a string are numbers? - FirstBornAlbratross - Apr-11-2023 OK I figured it out. String splice + check. (menator01's solution) Simple. Thanks for the replies. All the best. RE: How do I check if the first X characters of a string are numbers? - deanhystad - Apr-11-2023 menator's solution doesn't work if the string is shorter than 3 characters. for string in ("123ab", "12.3ab", "12", "123", "a123"): print(string, string[:3].isdigit()) 12 passes as a string that starts with 3 digits.
RE: How do I check if the first X characters of a string are numbers? - menator01 - Apr-12-2023 Could use an extra condition check for string in ('123ab', '12.3ab', '12', '123', 'a123'): if string[:3].isdigit() and len(string[:3]) >= 3: print(string)output:
RE: How do I check if the first X characters of a string are numbers? - jefsummers - Apr-12-2023 Minor point that hopefully does not apply - neither solution works for negative numbers. |