Python：良い構文がありますか？

Question

私がミスをしたところ、あなたが私に教えerror.Couldプログラミングに新たなんだと運動のような単純な電卓を作っているため、構文の私のコードを実行すると問題があるPython.Iを習い始め：

while True: 
    print("Options:") 
    print("Enter 'add' to add two numbers") 
    print("Enter 'substract' to substract two numbers") 
    print("Enter 'multiply' to multiply two numbers") 
    print("Enter 'divide' to divide two numbers") 
    print("Enter 'quit' to end the program") 
    user_input = input(":") 

    if user_input == "quit": 
     break 

    elif user_input == "add": 
     ... 
    elif user_input == "substract": 
     ... 
    elif user_input == "multiply": 
     ... 
    elif user_input == "divide": 
     ... 
    else: 
     print("Unknown input") 

    elif user_input == "add": 
     num1 = float(input("Enter a number:")) 
     num2 = float(input("Enter another number:")) 
     result = str(num1 + num2) 
     print("The answer is:" + result) 

    elif user_input == "substract": 
     num1 = float(input("Enter a number:")) 
     num2 = float(input("Enter another number:")) 
     result = str(num1 - num2) 
     print("The answer is:" + result) 

    elif user_input == "multiply": 
     num1 = float(input("Enter a number:")) 
     num2 = float(input("Enter another number:")) 
     result = str(num1 * num2) 
     print("The answer is:" + result) 

    elif user_input == "divide": 
     num1 = float(input("Enter a number;")) 
     num2 = float(input("Enter another number:")) 
     result = str(num1/num2) 
     print("The answer is:" + result) 

今後のお返事ありがとうございます！

Answer 1

2番目のelif文はelse文の後にあるためです。また、私はZeroDivisionError

while True: 
    print("Options:") 
    print("Enter 'add' to add two numbers") 
    print("Enter 'substract' to substract two numbers") 
    print("Enter 'multiply' to multiply two numbers") 
    print("Enter 'divide' to divide two numbers") 
    print("Enter 'quit' to end the program") 
    user_input = input(":") 

    if user_input == "quit": 
     break 
    elif user_input == "add": 
     num1 = float(input("Enter a number:")) 
     num2 = float(input("Enter another number:")) 
     result = str(num1 + num2) 
     print("The answer is:" + result) 

    elif user_input == "substract": 
     num1 = float(input("Enter a number:")) 
     num2 = float(input("Enter another number:")) 
     result = str(num1 - num2) 
     print("The answer is:" + result) 

    elif user_input == "multiply": 
     num1 = float(input("Enter a number:")) 
     num2 = float(input("Enter another number:")) 
     result = str(num1 * num2) 
     print("The answer is:" + result) 

    elif user_input == "divide": 
     num1 = float(input("Enter a number;")) 
     num2 = float(input("Enter another number:")) 
     # Example of a Try/Catch block to avoid ZeroDivisionError 
     try: 
      result = str(num1/num2) 
      print("The answer is:" + result) 
     except ZeroDivisionError: 
      print("Can't divide by 0") 
    else: 
     print("Unknown input")