Add user input to a list in Python

Add user input to a list in Python #

To add user input to a list in Python:

1. Declare a variable that stores an empty list.
2. Use a range to iterate N times.
3. On each iteration, prompt the user for input.
4. append the value to the list.

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shopping_list = []

list_length = 3

for idx in range(list_length):
    item = input('Enter item to buy: ')
    shopping_list.append(item)

print(shopping_list)  # 👉️ ['apple', 'banana', 'kiwi']

The code sample prompts the user for input 3 times and adds each value to the list.

The list.append() method adds an item to the end of the list.

The example uses the range class, but you can also use a while loop if you want to make sure the list has a length of at least N items.

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shopping_list = []

max_length = 3

while len(shopping_list) < max_length:
    item = input('Enter item to buy: ')
    shopping_list.append(item)

print(shopping_list)  # 👉️ ['apple', 'banana', 'kiwi']

If the list has a length of less than 3, we keep prompting the user for input.

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shopping_list = []

max_length = 3

while len(shopping_list) < max_length:
    item = input('Enter item to buy: ')

    # 👇️ make sure item is not in list before appending
    if item not in shopping_list:
        shopping_list.append(item)

print(shopping_list)  # 👉️ ['apple', 'banana', 'kiwi']

We used an if statement to check if the value the user entered isn't in the list before appending it.

The in operator operator tests for membership. For example, x in l evaluates to True if x is a member of l, otherwise it evaluates to False.

x not in l returns the negation of x in l.

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user_input = ''

while user_input.count(' ') < 2:
    user_input = input('Enter at least 3 space-separated shopping items: ')


shopping_list = user_input.split(' ')


print(shopping_list)  # 👉️ ['apple', 'banana', 'kiwi']

Note that this approach is a bit harder to validate.

The str.split() method splits the original string into a list of substrings using a delimiter.

The method takes the following 2 parameters:

If the separator is not found in the string, a list containing only 1 element is returned.