Problem with while loop. Program doesn't see an element of a list

Question

This is the task: Using while loop, if statement and str() function; iterate through the list and if there is a 100, print it with its index number. i.e.: "There is a 100 at index no: 5"

If I code like this -

lst = [10, 99, 98, 85, 45, 59, 65, 66, 76, 12, 35, 13, 100, 80, 95]
i = 0
while i < len(lst):
    if lst[i] == 100:
        print("There is a 100 at index no:", str(i))
    i += 1

, then everything is fine but if I try using user inputted list instead of a set list the code is not working:

lst = input('Enter your nums:').split(',')
entered_data = list(lst)
i = 0
while i < len(entered_data):
    if entered_data[i] == 100:
        print("There is a 100 at index no:", str(i))
    i += 1

I don't understand why is that so. Please, help.

Floh · Accepted Answer · 2022-04-10 12:52:49Z

2

The input generates a string.

This string, you split it on coma, but it is still a list of strings.

Then you should cast the type of your entry.


entered_data = input('Enter your nums:')
lst = entered_data.split(",")
for indice, elt in enumerate(lst):
    try:
        if int(elt) == 100:
            print(f"There is a 100 at index no:{indice}")
    except ValueError:
        print(f"The entered value {elt} at indice {indice} is invalid. It must be an integer. It will be ignored.")

I replaced your while with a for that is a more pythonic way to achieve the same goal.

edited Apr 10, 2022 at 12:52

answered Apr 10, 2022 at 8:50

Floh

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1 Comment

user18761257 Over a year ago

Thank you for your answer, I got my mistake. I understand that for is better in this case, but according to task one should use while.

Dismas · Accepted Answer · 2022-04-10 08:57:05Z

When you input elements, input function takes the input as string(str), not integers as you may be knowing.

a simple solution would be casting the element into an integer and all is done. So the code would be like

lst = input('Enter your nums:').split(',')
entered_data = list(lst)
i = 0
while i < len(entered_data):
    if int(entered_data[i]) == 100:
        print("There is a 100 at index no:", str(i))
    i += 1

Note that, the changed line is where you are comparing the element with integer 100. You can also print the 'entered_data', you will be able to see the single quotes around the single elements(I am using a jupyter notebook)

The code to show the list elements

lst = input('Enter your nums:').split(',')
entered_data = list(lst)
print(entered_data)
i = 0
while i < len(entered_data):
    if int(entered_data[i]) == 100:
        print("There is a 100 at index no:", str(i))
    i += 1

It's output is

Enter your nums:41,56,100,4
['41', '56', '100', '4'] 
There is a 100 at index no: 2

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