How can I check if a string represents an int, without using try/except?

Question

Is there any way to tell whether a string represents an integer (e.g., \'3\', \'-17\' but not \'3.14\' or \'asf

Answer 1

I suggest the following:

import ast

def is_int(s):
    return isinstance(ast.literal_eval(s), int)

From the docs:

Safely evaluate an expression node or a string containing a Python literal or container display. The string or node provided may only consist of the following Python literal structures: strings, bytes, numbers, tuples, lists, dicts, sets, booleans, and None.

I should note that this will raise a ValueError exception when called against anything that does not constitute a Python literal. Since the question asked for a solution without try/except, I have a Kobayashi-Maru type solution for that:

from ast import literal_eval
from contextlib import suppress

def is_int(s):
    with suppress(ValueError):
        return isinstance(literal_eval(s), int)
    return False

¯\_(ツ)_/¯