代碼來模擬.split（）函數在Python中的作用

Question

我需要爲學校項目製作一個程序。它必須執行Python中的.split()函數。但我必須從頭開始編寫它。

到目前爲止，我無法得到它添加任何超過一個空間的列表，我需要它添加無限數量的字符串。如果我給它多個字符，它就不會離開循環。我也不允許使用break。

sent = input("Give a sentence here:") 

List=[] 
Bpoint=0 
Epoint=0 
inString=[Bpoint,Epoint] 

Epoint=+1 
x=True 
while x==True: 
    if Epoint >= len(sent): 
      x=False 
    elif Epoint < len(sent): 
     if sent[Epoint] == chr(32): 
      List.append(inString[Bpoint:Epoint]) 
      Bpoint=Epoint + 1 
      x=False 
      if Epoint >= len(sent): 
       x=False 
      elif Epoint < len(sent): 
       x=True 
     elif sent[Epoint] != chr(32): 
      if Epoint >= len(sent): 
       x=False 
      elif Epoint < len(sent): 
       x=True 
      Epoint=+1 
     else: 
      print ("Somethings wrong. Close and start over.") 
print (List) 

Answer 1

下面是我將如何解決這個問題。

首先，重命名變量，收拾風格：

sentence = input("Give a sentence here:") 

results = [] 
word_start = 0 
word_end = 0 
in_string = [word_start, word_end] 

word_end = 1 
running = True 

while running: 
    if word_end >= len(sentence): 
     running = False 
     continue 

    # If we get here, we know that `word_end < len(sentence)` 
    if sentence[word_end] == " ": # chr(32) was just confusing 
     results.append(sentence[word_start:word_end]) # Note that using inString was wrong here 
     word_start = word_end + 1 
     running = False 
     if word_end >= len(sentence): 
      running = False 
     else: # We know `word_end < len(sent)` must be True 
      running = True 

    else: # We know `sentence[word_end] != " "` must be True, no need to check 
     if word_end >= len(sent): 
      running = False 
     else: # No need for the elif check, because logic 
      running = True 
     word_end += 1 # Fixed typo error =+ vs += 
    # else: The 'something wrong' could never be reached. Either a character is a space, or not a space - there is no 3rd option! 

print(results) 

的代碼是從一個結構上看大致維持不變，但至少現在它更容易看到發生了什麼事情。下一階段是開始修復結構。我注意到的第一件事是我們有詞的開始和結束詞計數器，我們需要手動維護它們。這有點難看，所以我們可以用一個for循環代替while循環，這個循環在句子上是enumerate。我還注意到，in_string不能正常使用，所以我們將擺脫它：所以現在

sentence = input("Give a sentence here:") 

results = [] 
word_start = 0 

for current_index, letter in enumerate(sentence): 

    if sentence[current_index] == " ": 
     # We've found a split between two words. See if we can add the previous word 
     word = sentence[word_start:current_index] 
     results.append(word) 
     word_start = current_index + 1 

     # Look at all the counter logic we've removed! 

print(results) 

我運行它，我發現它沒有找到的最後一個字：

Give a sentence here:Hi Tom this is a test 
['Hi', 'Tom', 'this', 'is', 'a'] 

所以在我們到了句子結尾之後，我們正在退出循環，因爲我們沒有足夠的空間來觸發add-word代碼。我們可以通過輸入「你好Tom這是一個測試」（注意最後一個空格）證明這個理論：

Give a sentence here:Hi tom this is a test 
['Hi', 'tom', 'this', 'is', 'a', 'test'] 

好了，這就是問題所在，現在我們需要解決它。我會把它留給你:-)之後還有幾件事情需要改進/修正（如果你輸入"Hello world"，會發生什麼？），但你需要親自發現它們！祝你好運！