Itertools 的问题 - 下一个函数（初级 Python 用户）

Question

我在 pycharm 中弄乱了 while 和 for 循环以更好地理解它们，并且我创建了一个操作音乐播放器的模型游戏，其中涉及我一直在学习和研究的一些功能和循环。前任。您可以输入诸如“随机播放”之类的命令，然后从歌曲列表中随机播放一首歌曲。

问题是“下一个”命令不起作用。我无法从列表中播放“下一首”歌曲。本质上，我希望命令在每次输入时循环播放歌曲列表。但无论我如何使用“下一首”功能，它仍然只返回列表中的第一首歌曲。

我尝试将 next() 函数移到代码的其他部分，但它仍然不起作用。您建议我在代码中进行哪些更改以使“下一个”命令起作用？

import random
import itertools
command = ""
player_on = False
paused = False
songs = iter([
    "Baby One More Time",
    "Hands Up",
    "I Believe in a Thing Called Love",
    "Unchained Melody",
    "Come On Eileen",
    "I Want It That Way"
])
next_song = next(songs, "end of playlist")

while True:
    command = input("What do you want to do?: ").lower()
    if command == "play":
        if player_on and not paused:
            print("Player is already on.")
            paused = False
        elif player_on and paused:
            paused = False
            print("un-paused")
        else:
            player_on = True
            paused = False
            print("Playing.")
    elif command == "pause":
        if paused and player_on:
            paused = True
            print("player already paused.")
        elif player_on and not paused:
            print(". . .")
            paused = True
        else:
            print("Turn player on first.")
    elif command == "shuffle":
        if player_on:
            print("Shuffles . . .")
            print(random.choice(songs))
        else:
            print("Turn player on first")
    elif command == "next":
        if player_on:
            paused = False
            print(f"Next song: {next_song}")
        else:
            print("Turn player on first.")
    elif command == "quit":
        if not player_on:
            print("Player is already off.")
        else:
            player_on = False
            break
    else:
        print("I don't understand that command.")

Answer 1

使用索引current_song_index 跟踪当前歌曲，在循环前用0 对其进行初始化，并在每个“下一个”命令前推进。

import random
import itertools
command = ""
player_on = False
paused = False
songs = [
    "Baby One More Time",
    "Hands Up",
    "I Believe in a Thing Called Love",
    "Unchained Melody",
    "Come On Eileen",
    "I Want It That Way"
]

current_song_index = 0

while True:
    command = input("What do you want to do?: ").lower()
    if command == "play":
        if player_on and not paused:
            print("Player is already on.")
            paused = False
        elif player_on and paused:
            paused = False
            print("un-paused")
        else:
            player_on = True
            paused = False
            print("Playing.")
    elif command == "pause":
        if paused and player_on:
            paused = True
            print("player already paused.")
        elif player_on and not paused:
            print(". . .")
            paused = True
        else:
            print("Turn player on first.")
    elif command == "shuffle":
        if player_on:
            print("Shuffles . . .")
            print(random.choice(songs))
        else:
            print("Turn player on first")
    elif command == "next":
        if player_on:
            paused = False
            current_song_index += 1
            if current_song_index < len(songs):                
                print(f"Next song: {songs[current_song_index]}")
            else:
                print('End of playlist')
                current_song_index = 0
        else:
            print("Turn player on first.")
    elif command == "quit":
        if not player_on:
            print("Player is already off.")
        else:
            player_on = False
            break
    else:
        print("I don't understand that command.")