user_input（）接受0个位置参数，但给定1个错误

Question

I am a beginner to Python and I thought it was a good idea to make a simple calculator, at the start it should ask the user for which operation it wants. Then loop through accordingly.

I did try changing certain things but it didn't help

Here's the code:

def user_input():
    operation_choice = (str(input("What operation would you like to perform?: ")))


while user_input("add"):
    def add_numbers():
        val1 = int(input("Enter your first value here: "))
        val2 = int(input("Enter your second value here: "))
        total = val1 + val2
        print(total)

while user_input():
    def subtract_numbers():
        val1 = int(input("Enter your first value here: "))
        val2 = int(input("Enter your second value here: "))
        total = val1 - val2
        print(total)

while user_input():
    def multiply_numbers():
        val1 = int(input("Enter your first value here: "))
        val2 = int(input("Enter your second value here: "))
        total = val1 + val2
        print(total)

while user_input():
    def divide_numbers():
        val1 = int(input("Enter your first value here: "))
        val2 = int(input("Enter your second value here: "))
        total = val1 + val2
        print(total)

    add_numbers()
    subtract_numbers()
    multiply_numbers()
    divide_numbers()
user_input()

Answer 1

I've taken the liberty of rearranging a few things.

def user_input():
    operation_choice = (str(input("What operation would you like to perform?: ")))
    if operation_choice == 'add':
        add_numbers()
    elif operation_choice == 'subtract':
        subtract_numbers()
    elif operation_choice == 'multiply':
        multiply_numbers()
    elif operation_choice == 'divide':
        divide_numbers()

def add_numbers():
    val1 = int(input("Enter your first value here: "))
    val2 = int(input("Enter your second value here: "))
    total = val1 + val2
    print(total)

def subtract_numbers():
    val1 = int(input("Enter your first value here: "))
    val2 = int(input("Enter your second value here: "))
    total = val1 - val2
    print(total)

def multiply_numbers():
    val1 = int(input("Enter your first value here: "))
    val2 = int(input("Enter your second value here: "))
    total = val1 + val2
    print(total)

def divide_numbers():
    val1 = int(input("Enter your first value here: "))
    val2 = int(input("Enter your second value here: "))
    total = val1 + val2
    print(total)

user_input()

Written this way, the program will perform one operation and then exit. If you want it to keep asking for more operations, then wrap the last user_input() in an infinite loop like this:

while True:
    user_input()

Then the program will go on running until you press Ctrl-C.