How to take a loop and turn it into a function I can call?-CodePudding

I'm new to python and am working on a simple calculator program for practice. I have created a loop for input validation but want to find a way to make my working function cleaner. Below is the original function that works.

def calculator():
first_num= input("First number: ")
second_num= input("Second number: ")
operation= ((input("Operation: (M, A, D, S)  "))).upper()
while True:
    if operation not in {"M", "A", "D", "S"}:
        print("Invalid input: ")
        operation = (input("Operation: (M, A, D, S)  ")).upper()
    else:
        break
if operation == "M":
    multiply(first_num,second_num)
elif operation == "D":
    divide(first_num,second_num)
elif operation == "A":
    add(first_num,second_num)
elif operation == "S":
    sub(first_num,second_num)

Below is what I've tried to do to make a separate function

def calculator():
first_num= input("First number: ")
second_num= input("Second number: ")
operation= ((input("Operation: (M, A, D, S)  "))).upper()
catch_operation(operation)
if operation == "M":
    multiply(first_num,second_num)
elif operation == "D":
    divide(first_num,second_num)
elif operation == "A":
    add(first_num,second_num)
elif operation == "S":
    sub(first_num,second_num)

def catch_operation(x):
while True:
     if x not in {"M","A","D","S"}:
        print("Invalid input: ")
        x = (input("Operation: (M, A, D, S)  ")).upper()
     else:
         return x

CodePudding user response：

Hmm. why do you still want to keep the while true in your function? why not just change it to:

def catch_operation(x):
while x not in {"M","A","D","S"}:
     print("Invalid input: ")
     x = (input("Operation: (M, A, D, S)  ")).upper()
return x

CodePudding user response：

Moving the loop into a separate function as you've done is fine, but note that you need to assign the output of catch_operation(operation) to the variable operation before you parse it:

operation = ((input("Operation: (M, A, D, S)  "))).upper()
operation = catch_operation(operation)