将用户输入附加到循环中的列表

Question

I'm new to python programming and I'm doing some experiments with it. Hoping my question is not too silly: I'm writing a little program that adds inputs to a list and print it when the input equals to 4, using a while loop. the problem is it never stops to add inputs and print the list. My code is:

S=input()
L=[]
while S!=4:
    L.append(S)
    if S==4:
        break
print(L)

Answer 1

The problem is because you one time read the input S = 1 for example, after that S always 1 so S never be 4 and your loop is never stoop, you must add your input to while :

list = []
number = -1
while number != 4:
    number = int(input())
    list.append(number)
print(list)

And if you check that S != 4 in while you don t need if statement in while`.

Answer 2

input() function returns string objects, so they can never be equal to 4 which is an int object.

To get out of the problem, replace 4 by '4' .

This will consider the '4' as a string as the equality will hold when you enter 4 as input

Answer 3

There is another big problem with your code you don't update S anymore a more right answer would be:

S=input()
L=[]
while S!=4:
    L.append(S)
    if S=="4":
        break
    S = input()
print(L)

If you'd not want everything to block waiting for new input then you might consider throwing in threading but if it's just to allow the user to add values to an array and stop doing that by adding 4 this could help

Answer 4

You've created an infinite loop in your code. You're not changing the value of S after you enter the loop. You should add get an another input from inside the loop like so:

S=input()
L=[]
while S!=4:
   L.append(S)
   S = input()
print(L)

In addition, The if condition in your code is useless since It's already set in the while loop declaration