如何在 Python 中的某个点重新启动程序

How to restart a program at a certain point in Python

提问by user2975375

So I made a very primitive and probably inefficient calculator today (first time using Python), and I want to be able to continue doing more problems, how would I do so? Here is my "calculator" app..

所以我今天做了一个非常原始而且可能效率很低的计算器（第一次使用Python），我希望能够继续做更多的问题，我该怎么做？这是我的“计算器”应用程序..

import time
print ("Welcome. This is a calculator that uses the function: A (operator) B.")
time.sleep(3.5)
print ("Available operators include: Addition, Subtraction, Multiplication, Division,        Exponent, and Remainder division.")
time.sleep(3.5)
a = float(input("Type in a value of A. "))
b = float(input("Type in a value of B. "))
operb = input("Would you like to: Add - Subtract - Multiply - Divide - Exponent - or Remainder? ")
opera = operb.lower()
if (opera) == "add":
    print ((a) + (b))
elif (opera) == "subtract":
    print ((a) - (b))
elif (opera) == "multiply":
    print ((a) * (b))
elif (opera) == "divide":
    print ((a) / (b))
elif (opera) == "exponent":
    print ((a) ** (b))
elif (opera) == "remainder":
    print ((a) % (b))
else:
    print ("Invalid operation.")
cont = input("Would you like to do another problem?")
cont = cont.lower()
if (cont) == "yes":
    ??
else:
    quit

I want it to restart at the "Type in a value of A." part, but I'm not sure how to do that.

我希望它在“键入 A 值”时重新启动。部分，但我不知道如何做到这一点。

回答by wvdz

The best way of doing this is probably with a while loop.

最好的方法可能是使用 while 循环。

while True:
    ## your code
    if cont != "yes":
        break
## quit

回答by tijko

You most likely going to want to use a whileloop, something like:

您很可能想要使用while循环，例如：

import time
print ("Welcome. This is a calculator that uses the function: A (operator) B.")
time.sleep(3.5)
print ("Available operators include: Addition, Subtraction, Multiplication, Division,        Exponent, and Remainder division.")
time.sleep(3.5)
while True:
    a = float(input("Type in a value of A. "))
    if a == 'q':  # set up a condition to end the program
        return

回答by Ramchandra Apte

Using a while loop, which keeps executing the block as long as the condition, cont == "yes", is true, i.e. it stops when the condition becomes false. After the while loop stops, the code after it is executed, in this case print("Bye, thanks for using the calculator.").

使用while 循环，只要条件cont == "yes"为真，它就会继续执行块，即当条件变为假时它停止。while 循环停止后，将执行其后的代码，在本例中为print("Bye, thanks for using the calculator.").

PS: The brackets around aand bin print ((a) + (b))are unnecessary. Similarly, the brackets around operaand contare also unnecessary. Also, the space after printmakes it a little hard to see which function the arguments are part of. I'd suggest you remove the space. Otherwise for a beginner-level programmer the code is good. Once you become more experienced with Python, you might want to use a dictionary mapping the names of the operator into the functions in the operatormodule.

PS：周围的括号a，并b在print ((a) + (b))有必要的。同样，围绕支架opera和cont也不必要。此外，后面的空格print使得很难看出参数属于哪个函数。我建议你删除空格。否则对于初学者级别的程序员来说，代码很好。一旦您对 Python 有了更多的经验，您可能希望使用字典将运算符的名称映射到operator模块中的函数中。

import time
print ("Welcome. This is a calculator that uses the function: A (operator) B.")
time.sleep(3.5)
print ("Available operators include: Addition, Subtraction, Multiplication, Division,        Exponent, and Remainder division.")
time.sleep(3.5)
cont = "yes" # So that the first time the while loop block will run
while cont == "yes":
    a = float(input("Type in a value of A. "))
    b = float(input("Type in a value of B. "))
    operb = input("Would you like to: Add - Subtract - Multiply - Divide - Exponent - or Remainder? ")
    opera = operb.lower()
    if (opera) == "add":
        print ((a) + (b))
    elif (opera) == "subtract":
        print ((a) - (b))
    elif (opera) == "multiply":
        print ((a) * (b))
    elif (opera) == "divide":
        print ((a) / (b))
    elif (opera) == "exponent":
        print ((a) ** (b))
    elif (opera) == "remainder":
        print ((a) % (b))
    else:
        print ("Invalid operation.")
    cont = input("Would you like to do another problem?")
    cont = cont.lower()

print("Bye, thanks for using the calculator.")