Python

Question

我已经有一段时间没写代码了，所以我想重新开始，但我的一些代码遇到了问题。

我想写一个简单的程序，它接受用户的输入并检查它是否全是没有空格的字母，并且长度小于 12。我一直在网上收到 "Invalid syntax" 错误17 每当我运行代码，指向 if 语句后的冒号，检查用户名是否只是字母且少于 12 个字符。我知道这意味着在那之前的线路上有错误，但是在哪里？

#import the os module

import os

#Declare Message

print "Welcome to Userspace - Your One-Stop Destination to Greatness!" + "\n" + "Please enter your username below." \
 + "\n" + "\n" + "Username must be at least 12 characters long, with no spaces or symbols." + "\n" + "\n"

#uinput stands for user's input

uinput = raw_input("Enter a Username: ")

#check_valid checks to see if arguement meets requirements

def check_valid(usrnameinput):
    if (usrnameinput != usrnameinput.isalpha()) or (len(usrnameinput) >= 12):
        os.system('cls')
        print "Invalid Username"
        return False
    else:
        os.system('cls')
        print "Welcome, %s!" % (usrnameinput)
        return True

#Asks for username and checks if its valid

print uinput
check_valid(uinput)

#Checks input to check_valid is correct, and if it is not, then ask for new username input and checks it again

while check_valid(uinput):
    return True
    break
else:
    print uinput
    check_valid(uinput)

print "We hope you enjoy your stay here at Userspace!"

更新 - 我对代码做了更多的尝试，唯一改变的是 while 条件为 if:

print uinput
check_valid(uinput)

#Checks input to check_valid is correct, and if it is not, then ask for new username input and checks it again

if check_valid(uinput):
    print uinput
    check_valid(uinput)

print "We hope you enjoy your stay here at Userspace!"

我运行这个代码，但得到这个错误：

  File "Refresher In Python.py", line 39
    return True
SyntaxError: 'return' outside function

抱歉我是个菜鸟。今天也刚加入 Stack Overflow。

Answer 1

我相信这就是你想要的。我建议将它分成两个函数，你的 check_valid() 和一个通用的 main() 函数。

def check_valid(usrnameinput):

    if (not usrnameinput.isalpha()) or (len(usrnameinput) >= 12):
        print("Invalid name")
        return False
    else:
        print("Welcome!")
        return True

def main():

    uinput = raw_input("Enter a Username: ")
    while not check_valid(uinput): #Repeatedly asks user for name.
        uinput = raw_input("Enter a Username: ")

main()

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