Question

我是Python的新手，想要知道如何使用if语句来结束一个程序来打印一条消息，因为当我的'stand'变量低于＆lt;时，它似乎不会发生。 5000. if语句加粗** **是我遇到问题的代码，它仍然打印出我想要的消息，但是，程序不会停止该消息，而是继续转到下一个代码（倒计时变量）。忽略'倒计时'。

这是我的代码的一部分。

   while stand <= 0 or mission > 10000: 
        try: 
            stand = int(input("Enter a VALID distance in metres: ")) 
        except ValueError: 
            print("Please enter a valid distance E.g 6000: ") 
    **if stand > 0 or stand < 5000: 
        print("ERROR, ERROR") 
        print("Launch cannot begin, the Mission Control and spectator stands are dangerously close at a distance of {}m.".format(mission)) 
        print("This launch site sucks! It must be demolished and rebuilt!") 
        print("Launch delayed.")**                   

    if stand >= 5000: 
        print("Fortunately the mission control and viewing stands are situated far enough.")              
    while countdown == 0 or countdown == "": 
        print("We need a person to countdown.")
        try:
            countdown = int(input("How many seconds would you like the countdown to be?: "))
        except ValueError:

Answer 1

使用break退出循环。

if stand > 0 or stand < 5000:
    print("ERROR, ERROR") 
    print("Launch cannot begin, the Mission Control and spectator stands are dangerously close at a distance of {}m.".format(mission)) 
    break

使用exit退出程序。

import sys
if stand > 0 or stand < 5000:
    print("ERROR, ERROR") 
    print("Launch cannot begin, the Mission Control and spectator stands are dangerously close at a distance of {}m.".format(mission)) 
    sys.exit(0)

Answer 2

您可以将代码置于正常运行状态。一个函数，您可以返回不同的值。在调用函数时，您可以检查返回的函数。您可以使用if

之类的条件

def func1():
       while stand <= 0 or mission > 10000: 
            try: 
                stand = int(input("Enter a VALID distance in metres: ")) 
            except ValueError: 
                print("Please enter a valid distance E.g 6000: ") 
        **if stand > 0 or stand < 5000: 
            print("ERROR, ERROR") 
            print("Launch cannot begin, the Mission Control and spectator stands are dangerously close at a distance of {}m.".format(mission)) 
            print("This launch site sucks! It must be demolished and rebuilt!") 
            print("Launch delayed.")
            return 1**                   

        if stand >= 5000: 
            print("Fortunately the mission control and viewing stands are situated far enough.")              
        while countdown == 0 or countdown == "": 
            print("We need a person to countdown.")
            try:
                countdown = int(input("How many seconds would you like the countdown to be?: "))
            except ValueError:
r = func1() 
if r == 1:
  print 'Error'

Answer 3

我们可以在if语句中使用break语句来终止。我们可以编写os.exit或sys.exit

而不是break

os._exit调用C函数_exit（），它立即终止程序。请注意声明“永远不会返回”。

sys.exit（）与引发SystemExit（）相同。它引发了一个Python异常，可能被调用者捕获。

import os

if stand > 0 or stand < 5000:
    print("ERROR, ERROR") 
    print("Launch cannot begin, the Mission Control and spectator stands are dangerously close at a distance of {}m.".format(mission)) 
    os.exit(0)

使用if语句结束脚本

3 个答案: