Question

这是我的代码中与该问题有关的部分：（我尽可能地减少了）

import os
import getpass

def PAUSE():
    input("= Press <ENTER> to continue...")

def clearscreen():
    os.system('cls' if os.name=='nt' else 'clear')

def loginscreen():
    clearscreen()
    print("==================================================================")
    print("=                              LOGIN                             =")
    print("==================================================================")
    print("= None Important.                                                =")
    print("==================================================================")
    username = input("= Please enter your username: ")
    password = getpass.getpass("= Please enter the password that belongs to that username: ")
    print("==================================================================")
    try:
        # I had too cut away the MariaDB Section for a MCVE, and thus i had to fill the dbusername and sdbpassword and isadmin, but without modifying relevant code. Thus i might have made a mistake in this array, dont use them alot sooo... if this were to occur i am sorry....
        ['dbusername = "stackoverflow", dbpassword = "stackoverflow", isadmin = "No"']
        for row in results:
            dbusername = row[0]
            dbpassword = row[1]
            isadmin = row [2]
            if username == dbusername:
                if password == dbpassword:
                    if isadmin == "Yes":
                        admin_main_menu()
                    elif isadmin == "No":
                        clearscreen()
                        main_menu()
########## For some reason the same problem arises when i use the commented away code under this comment.
#        clearscreen()
#        print("==============================================")
#        print("=         Unkown Username / Password         =")
#        print("==============================================")
#        PAUSE()
#        print("==============================================")
#        loginscreen()
    except:
        clearscreen()
        print("Failed to check codes. (Error: 5646FCJU), Contact N.S. Geldorp")
        PAUSE()       

def main_menu():
    clearscreen()
    print("=============================================")
    print("=                 Main Menu                 =")
    print("=============================================")
    print("= 1. All unimportant...                     =")
    print("= 5. Exit                                   =")
    print("=============================================")
    answer = input("= Please enter the number of the function you wish to use: ")
    print("=============================================")
    clearscreen()
    if answer == "1":
#        print_animals()
        print("Not needed")
        PAUSE()
    elif answer == "5":
#        pass
        print("Exiting...")
        exit()
    else:
        print("Unimportant...")
        PAUSE()
        main_menu()

现在，我删除了所有内容，但可能除了登录屏幕和标准主菜单的相关部分。当然，暂停和清除屏幕功能始终会出现在相关功能中。至少是我写的。现在发生的事情是，当我成功登录后，我进入菜单，然后决定退出，它向我显示了除登录屏幕之外的错误……我不明白，是吗？

Answer 1

这是演示1,442,633，它说明了为什么永远不要使用空白的except子句。

sys.exit()通过引发以下异常来工作：SystemExit。通常，该异常一直一直到解释器，然后由解释器捕获并正常退出。但是因为您的try / except代码可以捕获所有内容，所以它也可以捕获所有内容。因此您会看到自己的错误消息，而不是解释器退出。

您应该只抓住您知道可以处理的事情。我不确定您期望该代码有哪些异常，但是大概它们是数据库代码引发的异常。您应该确定可以提出哪些建议，并只接受那些建议，例如except TypeError:。

至少，您应该将您的除外限制为仅捕获实际错误，您可以使用except Exception:进行操作； SystemExit从BaseException继承，BaseException是Exception的父类，所有其他运行时错误都从该父类继承。但是，您实际上不应该这样做，您应该只捕获特定于的异常。

（还要注意，让for循环遍历数据库结果没有任何意义；我不明白您为什么这样做。）

稍后会在调用exit（）时显示自制异常。再次

1 个答案: