Short code with loop, function and list isn't working.Much appreciated if you help. (New at Python)

Question

Just started learning python, so I’m very thankful for anyone who can help.

Anyways the task is to define a function that takes a list of numbers and returns 3 values – how many positive numbers, negative numbers and zeroes there are in the list.

The main program I need to use a loop that gets the user to input however many numbers he wants (must be between 3 and 6, and this has to be checked). these numbers that the user inputs are to be added to a list. Then I have to call a function that uses the list as the argument and then print the results that the function returns.

using a loop is obligatory.

def three(z):
    np = 0
    nn = 0
    zeroes = 0
    
    for y in z:
        if x<0:
            nn+=1
        if x>0:
            np+=1
        if x==0:
            zeroes+=1
    
    print('there are ', np, ' positive numbersnthere are ', nn, ' negative numbersnthere are ', zeroes, ' zeros')
    
    return (np, nn, zeroes)

num_list = []

a = 0
n = eval(input('input a number (bigger than 3, smaller than 6): '))

while n>3 and n<6:
    if a < n:
        x = eval(input('input a number: '))
        num_list.append(x)
        a+= 1
    else:
        break
        
three(num_list)

I made a loop and a function, but I’m pretty sure I messed up at the loop or somewhere else because it looks like I’m using a lot of variables and it looks more complicated then it should probably be.

Asked By: Bing Chilling

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Source

Answer 1

First, you should avoid using eval to get the numerical value of the user input. Ignatius Reilly left a good link to explain why in a comment. Instead, just cast the string input to int using int(input(...)) instead.

Second, the issue is that you are comparing x to zero. x is not defined in your function, so it looks outside the function scope and then pulls what you defined as x there, which is the last user input from x = eval(input(...)). So a user that inputs -1, 2, 0, 4 will return (4, 0, 0) because it just compares 4 to 0 four times rather than each individual input. You made a simple mistake here and should’ve used y in your if statements.

Answered By: Michael Cao

Answer 2

Use a for-in-range loop to execute code n times.

Use int() to convert user input to an integer, not eval().

n = int(input("Input a number between 3 and 6: ")
if 3 <= n <= 6:
    nums = []
    for _ in range(n):
        x = int(input("Input a number: "))
        nums.append(x)
    print(three(list))
else:
    print("That's out of the range")

Answered By: Barmar

Short code with loop, function and list isn't working.Much appreciated if you help. (New at Python)

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