Question

我正在尝试在我的计算器中创建退出功能，我尝试了很多方法，但它不起作用。我不明白如何循环我的代码，没有网站解释该怎么做。

这是我的代码：

#Variables:
about = (" + Addition, - Subtraction, * Multiplication, / Division, ** Exponent, % Remainder")

print( )

print(about)

print( )

#Functions:

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

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

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

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

#Returns the power of num1 ** num2
def px(num1, num2):
    return num1 ** num2

#Returns the remainder of num1 % num2
def rem(num1, num2):
    return num1 % num2

#Main area where all the magic happens

#Wrong operation
def main():
    operation = input("What do you need me for? (+,-,*,/,**,%): ")
    if(operation != '+' and operation != '-' and operation != '*'
       and operation != '/' and operation != '**' and operation != '%'):

        #invalid operation
        print("Sorry, but that's not an operation")

    #What the operations should do
    else:
        var1 = int(input("Enter num1: "))
        var2 = int(input("Enter num2: "))

        if(operation == '+'):
            print(round(add(var1, var2), 2))

        elif(operation == '-'):
            print(round(sub(var1, var2), 2))

        elif(operation == '*'):
            print(round(mul(var1, var2), 2))

        elif(operation == '/'):
            print(round(div(var1, var2), 2))

        elif(operation == '**'):
            print(round(px(var1, var2), 2))

        elif(operation == '%'):
            print(round(rem(var1, var2), 2))


    #Exit function
    close = input ("Do you want to exit?: ")
    if(close == 'Yes' and close == 'yes'):
        close()

    elif(close == 'No' and close == 'no'):
        main()


main()

有人可以向我解释为什么它不起作用吗？

Answer 1

close无法同时为'No'和'no'，因此始终为假。

所以你可能意味着close == 'No' or close == 'no'。但更好的方法是close.lower() == 'no'

你正在做的不是循环而是递归（函数main调用自身）。如果你需要循环，那么试试这个：

while True:
    # your code

    close = input ("Do you want to exit?: ")
    if close.lower() == 'yes':
         break; # escapes the loop

Answer 2

将main()函数替换为以下函数：

def main():
    close = 'no'
    while close.lower() == 'no':
        print "inside while"
        operation = input("What do you need me for? (+,-,*,/,**,%): ")
        if operation not in ['+', '-', '*', '/', '**', '%']:
            print("Sorry, but that's not an operation")

        else:
            var1 = int(input("Enter num1: "))
            var2 = int(input("Enter num2: "))
            if(operation == '+'):
                print(round(add(var1, var2), 2))

            # ...

            elif(operation == '%'):
                print(round(rem(var1, var2), 2))

        close = input ("Do you want to exit?: ")

close初始化为'no'，因此循环至少执行一次。

您可以使用close == 'no' or close == 'No'代替lower()而不是close.lower() == 'no'

您应该使用：

if operation not in ['+', '-', '*', '/', '**', '%']:

而不是：

operation != '+' and operation != '-' and operation != '*' ...

Answer 3

即使用户说'是'或只是'y'

，我也想退出

while True:
    operation = input("What do you need me for? (+,-,*,/,**,%): ")
    if operation not in ['+', '-', '*', '/', '**', '%']:
        print("Sorry, but that's not an operation")
        continue
    ....
    close = input ("Do you want to exit?: ")
    if close and close[0].lower() == 'y':
        print('Bye')
        return

当用户只需按Enter键时，它也应该处理空字符串。

Answer 4

变量close不能同时为2个字符串。如果您不想更改代码，我建议您更改：if close == "Yes" and "yes":至if close == "Yes "or "yes"

如何使我的Python程序循环？

4 个答案: