在Python中更新字典

Question

您好，我正在构建一个小项目，用户可以在字典中输入新的键和值。如果用户输入已经输入字典的键或值，告诉他们需要输入新键或值，因为他们当前输入的键已经存在，是否可以显示信息？

这是我目前使用的一些代码。

# dictionary with key:values. 
reps = {'#':'A', '*':'M', '%':'N'} 

### The users guess 

print ("Now it's your turn to guess the rest of the letters!") 

###Score 
guesses = 0 

### Update the dictionary with the users new guesses 
while guesses < 10: 
    symbol = input('Please enter the symbol: ') 
    letter = input('Please enter the letter: ') 
    reps[symbol] = letter 

### Re printing the updated list 
    for line in lines_words: 
     txt = replace_all(line, reps) 
     print (txt) 
    guesses + 1 

Answer 1

可以测试现有的密钥和值in：

if symbol in reps: 
    print("You already defined that symbol") 

对于字母，你必须在字典中，以测试对所有值：

if letter in reps.values(): 
    print("You already defined that letter") 

你可以将两者结合起来：

if symbol in reps or letter in reps.values(): 
    print("You already used either the symbol or the letter")