如何在python中添加重启命令？ [复制]

Question

这是我写的一个简单的计算器，但完成后它不会重新启动应用程序 这是我的代码：

 def add(x, y):

 return x + y

def subtract(x, y):

return x - y

def multiply(x, y):

 return x * y

def divide(x, y):

 return x / y


 print("Select from the list bellow which oporation you want the calculator to do.")
 print("A.Add")
 print("S.Subtract")
 print("M.Multiply")
 print("D.Divide")

 choice = input("Enter choice(a/s/m/d):")
 if choice != 'a' and choice != 's' and choice != 'm' and choice != 'd':
     print (" the letter you intered is not in our lists!")

 num1 = int(input("Enter an interger as your first number: "))
 num2 = int(input("Enter an integer as second number: "))
 if choice == 'a':
    print(num1,"+",num2,"=", add(num1,num2))

 elif choice == 's':
    print(num1,"-",num2,"=", subtract(num1,num2))

 elif choice == 'm':
    print(num1,"*",num2,"=", multiply(num1,num2))

 elif choice == 'd':
    print(num1,"/",num2,"=", divide(num1,num2))
 else:
    print("Invalid input")
 input("press enter to close")

当它完成时，我希望它询问用户是否要重新启动。我在循环它不起作用时使用了不同的方法。

Answer 1

循环直到用户想要退出：

def main():
    print('Select from  the list below which operation you want the calculator to do.')
    print("A.Add")
    print("S.Subtract")
    print("M.Multiply")
    print("D.Divide")
    while True:
        choice = input("Enter choice(a/s/m/d) or q to quit:")
        if choice not in {"a", "s", "m", "d","q"}:
            print (" the letter you entered is not in our lists!")
            continue # if invalid input, ask for input again
        elif choice == "q":
            print("Goodbye.")
            break
        num1 = int(input("Enter an integer as your first number: "))
        num2 = int(input("Enter an integer as second number: "))
        if choice == 'a':
            print("{} + {} = {}".format(num1, num2, add(num1, num2)))
        elif choice == 's':
            print("{} - {} = {}".format(num1, num2, subtract(num1, num2)))

我使用 str.format 打印您的输出，if choice not in {"a", "s", "m", "d","q"} 使用 in 测试 membership 替换长 if 语句。

您可能希望将 int 输入包装在 try/except 中，以避免在用户输入不正确时程序崩溃。

try:
   num1 = int(input("Enter an interger as your first number: "))
   num2 = int(input("Enter an integer as second number: "))
except ValueError:
   continue

如果您想按照评论中的示例进行操作：

def main():
    print('Select from  the list below which operation you want the calculator to do.')
    print("A.Add")
    print("S.Subtract")
    print("M.Multiply")
    print("D.Divide")
    while True:
        choice = raw_input("Enter choice(a/s/m/d)")
        if choice not in {"a", "s", "m", "d","q"}:
            print (" the letter you entered is not in our lists!")
            continue
        num1 = int(input("Enter an integer as your first number: "))
        num2 = int(input("Enter an integer as second number: "))
        if choice == 'a':
            print("{} + {} = {}".format(num1, num2, add(num1, num2)))
        elif choice == 's':
            print("{} - {} = {}".format(num1, num2, subtract(num1, num2)))
        inp = input("Enter 1 to play again or 2 to exit")
        if inp == "1":
            main()
        else:
            print("thanks for playing")
            break

Answer 2

而不是这个：

if choice != 'a' and choice != 's' and choice != 'm' and choice != 'd' and choice != 'e':
        print (" the letter you intered is not in our lists!")
else:
        num1 = int(input("Enter an interger as your first number: "))
        num2 = int(input("Enter an integer as second number: "))

使用这个：

if choice != 'a' and choice != 's' and choice != 'm' and choice != 'd' and choice != 'e':
        print (" the letter you intered is not in our lists!")
elif choice==e:
        print("goodbye")
        break
else:
        num1 = int(input("Enter an interger as your first number: "))
        num2 = int(input("Enter an integer as second number: "))

Answer 3

您需要将处理用户输入的部分封装在一个 while 循环中。您还需要一个选项来在您的选择过程中中断该 while 循环。我添加了处理退出循环的输入值e。你的第一个 if 语句和最后的 else 语句是多余的，所以我也稍微改变了它们。

def add(x, y):
    return x + y

def subtract(x, y):
    return x - y

def multiply(x, y):
    return x * y

def divide(x, y):
    return x / y


while True:
    print("Select from the list bellow which oporation you want the calculator to do.")
    print("A.Add")
    print("S.Subtract")
    print("M.Multiply")
    print("D.Divide")
    print("E.Exit")

    choice = input("Enter choice(a/s/m/d/e):")
    if choice != 'a' and choice != 's' and choice != 'm' and choice != 'd' and choice != 'e':
        print (" the letter you intered is not in our lists!")
    else:
        num1 = int(input("Enter an interger as your first number: "))
        num2 = int(input("Enter an integer as second number: "))
        if choice == 'a':
            print(num1,"+",num2,"=", add(num1,num2))

        elif choice == 's':
            print(num1,"-",num2,"=", subtract(num1,num2))

        elif choice == 'm':
            print(num1,"*",num2,"=", multiply(num1,num2))

        elif choice == 'd':
            print(num1,"/",num2,"=", divide(num1,num2))
        elif choice == 'e':
            print("Goodbye")
            break