如果用户在 Python 中输入相同的字符串两次，我如何打印特定的消息？

Question

我正在练习我的 Python 技能。我目前在第 4 周，坚持做一项特定的任务。如果用户在我的 self.songs 输入中两次输入相同的字符串，我想打印一条消息“你不能两次输入同一首歌曲。再试一次”。

我该怎么做？另外，有没有办法让用户在输入他们喜欢的歌曲时使用逗号而不是空格来分隔每个字符串？

  class User:
    def __init__(self):
        self.name = ''
        self.songs = ()
        self.movies = ()
        self.sports = ()

    def tops(self):
        self.name = input("What's you're full name?:")
        while True:
            self.songs = input('Hi ' + self.name + ', what is your top 5 favorite songs?:').split()
            if len(self.songs) > 5:
                print('You entered more than 5 songs. Try again')
            elif len(self.songs) < 5:
                print('You entered less than 5 songs. Try again')
            elif len(self.songs) == 5:
                for song in self.songs:
                    print(song)
                confirm_input = input('Do you confirm?')
                if confirm_input == 'Yes':
                    print(type(self.songs))
                    print(self.songs)
                    break
                elif confirm_input == 'No':
                    continue


quizUser = User()
quizUser.tops()

Answer 1

您可以使用set 获取唯一元素，然后将其长度与答案长度进行比较

if len(set(self.songs)) != len(self.songs):
    print("You can't enter the same song twice. Try again")    
elif len(self.songs) > 5:
    print('You entered more than 5 songs. Try again')
elif len(self.songs) < 5:
    print('You entered less than 5 songs. Try again')
...

Answer 2

您可以使用set 获取不相同的元素，并使用!= 将其长度与普通列表进行比较。

将此添加到您的代码中：

elif len(set(self.songs)) != len(self.songs):
    print('You can\'t enter the same song twice. Try again')

顺便说一句，\' 表示转义 '。

整个代码：

class User:
        def __init__(self):
            self.name = ''
            self.songs = ()
            self.movies = ()
            self.sports = ()
    
        def tops(self):
            self.name = input("What's you're full name?:")
            while True:
                self.songs = input('Hi ' + self.name + ', what is your top 5 favorite songs?:').split()
                if len(self.songs) > 5:
                    print('You entered more than 5 songs. Try again')
                elif len(self.songs) < 5:
                    print('You entered less than 5 songs. Try again')
                elif len(self.songs) != len(set(self.songs)):
                    print('You can\'t enter the same song twice. Try again')
                elif len(self.songs) == 5:
                    for song in self.songs:
                        print(song)
                    confirm_input = input('Do you confirm?')
                    if confirm_input == 'Yes':
                        print(type(self.songs))
                        print(self.songs)
                        break
                    elif confirm_input == 'No':
                        continue
    
    
quizUser = User()
quizUser.tops()

Answer 3

您可以计算每个元素的出现次数，如果存在重复，则将 flag 设置为 1。
以下是修改后的代码：

class User:
    def __init__(self):
        self.name = ''
        self.songs = ()
        self.movies = ()
        self.sports = ()

    def tops(self):
        self.name = input("What's you're full name?:")
        while True:
            ########################################
            #Flag variable to check if the repetition occured
            flag = 0
            self.songs = input('Hi ' + self.name + ', what is your top 5 favorite songs?:').split()
            #Loop over the songs
            for i in self.songs:
                #Check the count of each song, if greater than 1 set flag variable to 1 and empty songs.
                if self.songs.count(i)>1:
                    print("You can't enter the same song twice. Try again")
                    self.songs = ()
                    flag = 1
            #Check if flag is 1, if true exit the current iteration
            if flag == 1:
                continue
            #######################################
            if len(self.songs) > 5:
                print('You entered more than 5 songs. Try again')
            elif len(self.songs) < 5:
                print('You entered less than 5 songs. Try again')
            elif len(self.songs) == 5:
                for song in self.songs:
                    print(song)
                confirm_input = input('Do you confirm?')
                if confirm_input == 'Yes':
                    print(type(self.songs))
                    print(self.songs)
                    break
                elif confirm_input == 'No':
                    continue


quizUser = User()
quizUser.tops()