[SOLVED]Can't tell what's wrong here

Question

Trying to make a code which detects numbers in a string and prints the smallest number into it (e.g "1 + 2 = 3" and output would be 1 or none if there are no numbers). However, my output is 1 none none none 1 none none none 1.
Code :
S = input()
a = []
for c in S:
if c >= '0' and c <= '9':
a.append(int(c))
print(min(a))
else:
print('None')

Answer 1

Try this

S = input()
a = []
for c in S:
if c >= '0' and c <= '9':
a.append(int(c))

if a == []:
print('None')
else:
print(min(a))

I placed your print(min(a)) external to your loop so it won't print on every iteration.
Let the loop do the work, then place an if/else condition on list(a) to show your final result

Answer 2

Instead of...if c >= '0' and c <= '9':
use c.isdigit() and take the print statement out of the loop....
Later... in a print statement do some thing like (I've not got my IDE on right now)

print(min(a) if len(a) else "none")

edit:- you dont even need the len (just checked), just do :
print(min(a) if a else "none")

Answer 3

You can use a regular expression to detect the numbers.

Answer 4

// ζοhιπ The code is recognising that format because it will be referring to the character ordinals

It does look unusual though & it was the first thing I checked

Answer 5

// Rik Wittkopp Yep that's true but we can filter a string and get numbers contained in that string (if we only want to filter)

Answer 6

// In fact, during this loop, your program didn't know "+" and "=" signs because those are not numbers but strings.

Answer 7

This code will also work for more than 1 digit numbers..

input : 111+34=145
output: 34

import re
pattern=re.compile(r"\d+")

my_string=input("Enter your string here : ")
numbers=re.findall(pattern,my_string)

if numbers:
print(min(numbers))
else:
print("None")

https://code.sololearn.com/cYbvw33Gi0Sb/?ref=app