此python代码中的错误

Question

while True: 
print ("Options") 
print ("Write 'Quit' if you want to exit") 
print ("Write '+'if you want to make an addition") 
print ("Write '-' if you want to make a sottration") 
print ("Write '*' if you want to make a moltiplication") 
print ("Write '/' if you wantto make a division") 
user_input == input(":") 
     if user_input == ("+") 
     num1 = float(input("Enter a number...") 
     num2 = float(input("Enter the second number...") 
     result = str(num1+num2) 
     print("The result is"+ result) 
     elif user_input == ("-") 
     num1 = float(input("Enter a number...") 
     num2 = float(input("Enter the second number...") 
     result = str(num1-num2) 
     print("The result is"+ result) 
     elif user_input == ("*") 
     num1 = float(input("Enter a number...") 
     num2 = float(input("Enter the second number...") 
     result = str(num1*num2) 
     print("The result is"+ result) 
     elif user_input == ("/") 
     num1 = float(input("Enter a number...") 
     num2 = float(input("Enter the second number...") 
     print ("The result is"+ result) 

这是我在python 2.7中创建的代码，但它不起作用。我认为存在缩进错误。你可以帮我吗？

Answer 1

解决您的压痕和各if-statement后加冒号以下，改变user_input == input(':')到​​：

while True: 
    print ("Options") 
    print ("Write 'Quit' if you want to exit") 
    print ("Write '+'if you want to make an addition") 
    print ("Write '-' if you want to make a sottration") 
    print ("Write '*' if you want to make a moltiplication") 
    print ("Write '/' if you wantto make a division") 
    user_input = input(":") # fix this line 
    if user_input == ("+"): 
     num1 = float(input("Enter a number...")) 
     num2 = float(input("Enter the second number...")) 
     result = str(num1+num2) 
     print("The result is"+ result) 
    elif user_input == ("-"): 
     num1 = float(input("Enter a number...")) 
     num2 = float(input("Enter the second number...")) 
     result = str(num1-num2) 
     print("The result is"+ result) 
    elif user_input == ("*"): 
     num1 = float(input("Enter a number...")) 
     num2 = float(input("Enter the second number...")) 
     result = str(num1*num2) 
     print("The result is"+ result) 
    elif user_input == ("/"): 
     num1 = float(input("Enter a number...")) 
     num2 = float(input("Enter the second number...")) 
     result = str(num1/num2) 
     print ("The result is"+ result) 

编辑：

下面是一个更好版本的代码，修复一些错误，就像读取字符串输入一样，避免除以零异常并删除float()类型的投射，因为在python 2.7 input()已经为你做了。

while True: 
    print("Options") 
    print("Write 'Quit' if you want to exit") 
    print("Write '+'if you want to make an addition") 
    print("Write '-' if you want to make a sottration") 
    print("Write '*' if you want to make a moltiplication") 
    print("Write '/' if you wantto make a division") 
    user_input = raw_input(":") 
    if user_input == '+': 
     num1 = input("Enter a number...") 
     num2 = input("Enter the second number...") 
     print('The result is {}'.format(num1+num2)) 
    elif user_input == '-': 
     num1 = input("Enter a number...") 
     num2 = input("Enter the second number...") 
     print('The result is {}'.format(num1-num2)) 
    elif user_input == '*': 
     num1 = input("Enter a number...") 
     num2 = input("Enter the second number...") 
     print('The result is {}'.format(num1*num2)) 
    elif user_input == '/': 
     num1 = input("Enter a number...") 
     num2 = input("Enter the second number...") 
     if num2 == 0: 
      print("Can't divide by zero.") 
     else: 
      print("The result is {}".format(num1/num2)) 

此外，通过其他用户的建议这里是一个改进版本：

while True: 
    print("Options") 
    print("Write 'Quit' if you want to exit") 
    print("Write '+'if you want to make an addition") 
    print("Write '-' if you want to make a sottration") 
    print("Write '*' if you want to make a moltiplication") 
    print("Write '/' if you wantto make a division") 
    user_input = raw_input(":") 
    num1 = input("Enter a number...") 
    num2 = input("Enter the second number...") 

    if user_input == "+": 
     result = str(num1+num2) 
    elif user_input == "-": 
     result = str(num1-num2) 
    elif user_input == "*": 
     result = str(num1*num2) 
    elif user_input == "/": 
     if num2 == 0: 
      result = "Can't divide by zero" 
     else: 
      result = str(num1/num2) 

    print("The result is", result)