string to int ValueError Python

Question

if the string is '007w', then when it tries to return '007w' as integer, i want it to return None and print('Cannot be converted). But without using the Try Except ValueError:

import random

def random_converter(x):
    selection = random.randint(1,5)
    if selection == 1:
        return int(x)
    elif selection == 2:
        return float(x)
    elif selection == 3:
        return bool(x)
    elif selection == 4:
        return str(x)
    else:
        return complex(x)


for _ in range(50):
    output = random_converter('007w')
    print(output, type(output))

i would use try-expect but with random.choice([int, float, bool, str, complex])(x) — Chris_Rands
– Chris_Rands, Commented Dec 9, 2019 at 16:07
Does this answer your question? How do I check if a string is a number (float)? — Sayse
– Sayse, Commented Dec 9, 2019 at 16:07
@user1558604 challenging to find different ways to solve things and get around things the hard way, so in future problems I'll have a more analytical approach — drleechy
– drleechy, Commented Dec 9, 2019 at 16:11

Nick Reed · Accepted Answer · 2019-12-09 16:09:51Z

5

You can use str.isdigit() to check whether a string in python can be parsed into a number or not. It will return true if all values are digits, and false otherwise.

Note that isdigit() is fairly limited in its ability - it can't handle decimal points or negative numbers. If you're expecting to parse anything more complicated than a positive integer, you may want to consider try/except instead.

def parse(in_str):
  if(in_str.isdigit()):
    return int(in_str)
  else:
    print('Cannot be converted')
    return(None)

print(parse("1234"))
print(parse("007w"))

1234
Cannot be converted
None

Demo

edited Dec 9, 2019 at 16:09

answered Dec 9, 2019 at 16:02

Nick Reed

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Comments

Jab · Accepted Answer · 2019-12-09 16:17:01Z

4

You can use random.choice for your decider and str.isdigit for checking if x can be converted:

def random_converter(x):
    selection = random.choice([int, float, bool, str, complex])
    if x.isdigit() or selection == bool:
        return selection(x)
    else:
        return None

edited Dec 9, 2019 at 16:17

answered Dec 9, 2019 at 16:10

Jab

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2 Comments

Sayse Over a year ago

The same still applies for str and float for example

Nick Reed Over a year ago

Now that's a pythonic answer. Almost feels taboo to think you can cast to any value in a string, +1

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