如何检查Python中是否只有一部分变量位于字符串旁边？

Question

我正在尝试让我的代码检查文档中是否已经存在某个单词。但是，在选择变量(username)时@遇到与文件中的预先存在的相同字母相同的字母，它认为该名称是拍摄的。例如，如果abcdefg 在文件中，如果我要对defg 或fg 或g，它会认为用户名已被占用。

def register():
    print("━━━━ACCOUNT CREATION━━━━")
    username = input("Create Username: ")
    with open("Login.txt", "r") as loginfile:
        if (username+",") in loginfile.read():
            print("Sorry, but that username is taken.")
            choice = input("Try again with a new name? (Y/N)")
            choice = choice.upper()

我的情况： 假设我有名字，Joe，它已经在文件中。如果我尝试创建一个只是 e 的用户名，那么它会认为是 Joe，因为它正在寻找逗号旁边的 e。

无论如何要解决这个问题？谢谢！

Answer 1

这应该可以工作

with open('login.txt', 'r') as LoginFile:
    # the split function splits a string to a list on mark
    Data = LoginFile.read().split(" ,") 
    if username in Data:
        # .....

如果这不是你想要的，试试这个内置模块：

https://docs.python.org/3/library/re.html

Answer 2

def register():
    print("━━━━ACCOUNT CREATION━━━━")

    # read the names from the file
    with open('Login.txt', 'r') as f:
        names = f.read().split(',')

    username = input("Create Username: ")

    for name in names:
        # check if any names end with this name have been created
        if name.endswith(username):
            # found
            print("Sorry, but that username is taken.")

            # we want to keep ask the user to select if
            # they enter something other than Y/N
            while True:
                # ask for the option
                option = input("Try again with a new name? (Y/N) ")
                # try again, we just rerun this function
                if option == 'Y':
                    register()
                    # don't ask any more
                    break
                elif option == 'N':
                    # exit if user chooses N
                    break
                # if the user chooses something else, continue
                # the loop and keep asking
                
            # if no names end with username, goto else
            break
    else:
        # name available, save it to the file
        print("Name created successfully:", username)
        new_names = names + [username]
        with open('Login.txt', 'w') as f:
            f.write(','.join(new_names))

我已经测试过了，请尝试看看它是否适合你。