Question

该程序在打印完第一行后退出，似乎没有进入while循环。我在这里走到了尽头，任何帮助都会受到赞赏。它的设计是在不同的目录中创建具有相同名称的文件

print ("What is the name of the command to create?: ")
#loops until program is done
exit = "placeholder"
while exit != exit:
#filename to use for directory creation
    cmd = input()
#combines cmd name with directory
    cmdDir = "/usr/bin/" + cmd
#makes sure something was entered as a cmd name
    if cmdDir == "/usr/bin/":
        print ("Command name invalid. Try again: ")

    else: 
#creates file at directory with cmd name
        open (cmdDir, 'a')
            print ("Will this command have a python extension?: ")
#loops until program is done
            while exit != exit:
                decision = input()
#combines cmd name with python directory
                pythonDir = "/root/python/" + cmd + ".py"
                if decision == "yes":
#creates directory              
                    open (pythonDir, 'a')
                    print ("Command directories " + cmdDir + " and" + pythonDir + " created. ")
#sets program to exit while loops
                    exit = "exit"
                elif decision == "no":
                    print ("Command directory " + cmdDir + "created. ")
#sets program to exit while loops
                    exit = "exit"
                else:
                    print ("Enter yes or no: ")

ps：使用4空格缩进手动格式化这是一个痛苦的屁股，自动缩进是如何工作的？

Answer 1

while exit != exit:

exit 总是等于exit，因为它们是相同的变量（在某些情况下此规则有例外但对字符串不存在输入Python）。所以表达式总是假的，你永远不会进入循环体。

您可能打算这样做：

while exit != 'exit':

将变量与固定字符串常量进行比较。

Answer 2

while exit != exit:

是什么让你搞砸了。由于它们是相同的变量exit将始终等于exit。由于exit是一个字符串，因此无法解决此问题。

所以您可能希望使用的代码可以是while exit != 'exit':这将阻止程序退出第1行。原因是如果变量exit没有值'exit'然后程序将运行。

希望这有帮助。

为什么这个python程序会自动关闭？

2 个答案: