替換字符串中的 substring：Python

Question

我正在嘗試根據用戶輸入不斷替換字符串中的子字符串，但我的 string.replace 語法似乎用用戶輸入的 substring 替換了整個字符串。 這是代碼：

import re
secret_word  = 'COMPUTER'    
clue = len(secret_word) * '-'   # this step gives the user the nos of characters in secret_word
user_guess = input("Type a single letter here, then press enter: ")
user_guess = user_guess.upper()
if user_guess in secret_word:
    index = [match.start() for match in re.finditer(user_guess, secret_word)] # this finds the index of the user guess in secret_word                                                     
    print(index)
    for i in index:
        clue  = clue.replace(clue[i], user_guess)
        print("The word now looks like this: "+ clue)

我不確定為什么它不只替換子字符串。

Answer 1

原因是clue = clue.replace(clue[i], user_guess) 。 clue[i]開頭總是等於'*' ，因此替換 function 將用 user_guess 替換所有字符。

一種解決方案是將clue更改為列表而不是字符串clue = len(secret_word) * ['-']並將替換操作替換為clue[i] = user_guess

不要忘記更新打印操作：在 print( "".join(clue) print("The word now looks like this: "+ clue) clue

Answer 2

在 python 中，當您使用 str.replace str.replace(x, substitution)時，它會將每次出現的x substituion為字符串str中的替換。

在開始時，變量clue包含--------字符串，因此您的替換方法被稱為clue.replace('-', U)考慮到，用戶提供了輸入u ，這反過來替換了每次出現-即UUUUUUUU的整個字符串clue 。

實現此目的的一種方法是將您的代碼更改為以下內容：

import re
secret_word = 'COMPUTER'
clue = len(secret_word) * '-'   # this step gives the user the nos of characters in secret_word
user_guess = input("Type a single letter here, then press enter: ")
user_guess = user_guess.upper()
if user_guess in secret_word:
    index = [match.start() for match in re.finditer(user_guess, secret_word)]  # this finds the index of the user guess in secret_word
    print(index)
    for i in index:
        clue = clue[:i] + user_guess + clue[i:]
        print("The word now looks like this: "+ clue)

Answer 3

secret_word  = 'COMPUTER'
clue = str(len(secret_word) * '-')   # this step gives the user the nos of characters in secret_word
user_guess = input("Type a single letter here, then press enter: ")
user_guess = user_guess.upper()

if user_guess in secret_word:
    index = user_guess.find(user_guess) # this finds the index of the user guess in secret_word
    clue = clue[:index] + user_guess + clue[index+1:]
    print("The word now looks like this: " + clue)

試試這個你不需要正則表達式