如何检查列表/元组中的用户输入？

Question

基本上我希望我的程序做的是：

new_ch = input("What channel would you like to switch to?")
if new_ch in channels:
      print("You're now on channel,", new_ch,".")
else:
       print("That's not a valid channel.")

无论我做什么，它都会在错误分支上不断打印语句“那不是一个有效的频道”。有没有办法让我的程序使用用户输入搜索我的频道列表/元组？我的频道列表包含变量名 ex。

Ch1 = "Ch1 - Fox News"
Ch2 = "Ch2 - PBS"

Etc.

channels = [Ch1, Ch2, Ch3, ... Ch10]

Answer 1

好的，如果输入是“ch1”并且您希望输出是“Ch1 - Fox News”，那么您的 if 语句不正确。

因为您将“Ch1”与 ['Ch1 - Fox News', 'Ch2 - PBS'] 进行比较：

>>> channels = [Ch1, Ch2]
>>> channels
['Ch1 - Fox News', 'Ch2 - PBS']

所以要纠正这个问题，你需要使用字典，方法如下：

Ch1 = "Ch1 - Fox News"
Ch2 = "Ch2 - PBS"
channels = {"CH1":Ch1,"CH2": Ch2}
new_ch = input("What channel would you like to switch to?")
What channel would you like to switch to?"ch1"
if new_ch.upper() in channels:
    print("You're now on channel,", channels[new_ch.upper()],".")
else:
    print("That's not a valid channel.")


 ("You're now on channel,", 'Ch1 - Fox News', '.')

上层函数只是大小写无关。

更新

---

随机化：

elif choice == "2":
    ch = random.choice(channels.keys())
    print("You're now on channel", channels[ch],".")

打印频道列表：

elif choice == "1":
    print("\n")
    for item in channels:
        print(channels[item])