Question

#Returns the sum of num1 and num2
def add(num1, num2):
    return num1 + num2

#Returns the result of subtracting num1 - num2
def sub(num1, num2):
    return num1 - num2

#Returns the result of multiplying num1 * num2
def mul(num1, num2):
    return num1 * num2

#Returns the result of dividing num1 / num2
def div(num1, num2):
    return num1 / num2


def main():
    operation = input("What do you want to do(+,-,*,/): ")
    if(operation != '+' and operation != '-' and operation != '*' and operation != '/' ):
       #invaid operation
       print("you must enter a valid operation")
    else:
        var1 = int(input("emter num1: "))
        var2 = int(input("Enter num2: "))
            if(operation == '*'):
             print(add(var1, var2))
             elif(operation == '/'):
                print(div(var1, var2))
            elif(operation == '-'):
                print(sub(var1, var2))
            elif:
                print(mul(var1, var2)) 


main()

Answer 1

您的整个if和elif块是错误的。正确的意图如下所示：

else:
    var1 = int(input("emter num1: "))
    var2 = int(input("Enter num2: "))
    if(operation == '*'):
        print(add(var1, var2))
    elif(operation == '/'):
        print(div(var1, var2))

，依此类推。您应先考虑reading more about indentation in python，然后再继续。这不仅是Python所必需的，而且也是每种语言（据我所知）的最佳实践，以使您的代码更具可读性。

Answer 2

Python使用空格来决定代码如何组合在一起。

这运行bar并且baz为foo为真：

如果foo：酒吧（） baz（）

如果bar为真，则运行foo，并且始终运行baz：

if foo:
  bar()
baz()

这根本不起作用：

if foo:
  bar()
   baz()

如果缩进不一致，Python将抛出错误并放弃。

就您而言，这里的缩进似乎很糟糕：

if(operation == '*'):
 print(add(var1, var2))
 elif(operation == '/'):
    print(div(var1, var2))
elif(operation == '-'):
    print(sub(var1, var2))
elif:
    print(mul(var1, var2))

您的print缩进了少于三个空格（这是if语句的块的一部分），而后面的elif块缩进了三个空格（它应该与if语句处于同一级别）

if(operation == '*'):
  print(add(var1, var2))
elif(operation == '/'):
  print(div(var1, var2))
elif(operation == '-'):
  print(sub(var1, var2))
elif:
  print(mul(var1, var2))

顺便说一句，乘法和加法都被翻转了！

Answer 3

您的缩进被弄乱了。试试这个：

#Returns the sum of num1 and num2#Returns 
def add(num1, num2):
return num1 + num2
#Returns the result of subtracting num1 - num2
def sub(num1, num2):
return num1 - num2
#Returns the result of multiplying num1 * num2
def mul(num1, num2):
return num1 * num2
#Returns the result of dividing num1 / num2
def div(num1, num2):
return num1 / num2


def main():
    operation = input("What do you want to do(+,-,*,/): ")
    if(operation != '+' and operation != '-' and operation != '*' and operation != '/' ):
       #invaid operation
       print("you must enter a valid operation")
    else:
        var1 = int(input("Enter num1: "))
        var2 = int(input("Enter num2: "))
    if(operation == '*'):
        print(add(var1, var2))
    elif(operation == '/'):
        print(div(var1, var2))
    elif(operation == '-'):
        print(sub(var1, var2))
    else:
        print(mul(var1, var2)) 


main()

当我运行此脚本时，它在else行中告诉IdentationError，为什么？

3 个答案: