正則表達式差異+和*

Question

這可能是一個轉儲問題。但我必須要求澄清它。

我有一個文本

string = ''' t Network Questions 
Is there   something like a (readied) charge in 5e? 
Can you use a 
    Bonus Action on a  turn''' 

文本被有意分散。我偶然發現了這個疑問。

print re.sub(r'\s+',' ',string) 

t Network Questions Is there something like a (readied) charge in 5e? Can you use a Bonus Action on  a turn 

看看下一條語句。

print re.sub(r'\s*',' ',string) 

t N e t w o r k Q u e s t i o n s I s t h e r e s o m e t h i n g l i k e a (r e a d i e d) c h a r g e i n 5 e ? C a n y o u u s e a B o n u s A c t i o n o n a t u r n 

唯一的區別是*和+。那麼，到底什麼意思是0或更多的出現和更多的出現。任何人都可以解釋爲什麼當我們使用*時，單詞之間的空格。

Answer 1

如何+匹配字符串

Is there   something like 
    | 
\s #one space 

Is there   something like 
     | 
     \s+ #one or more space 

Is there   something like 
     | 
     \s+ #one or more space 

# And so on untile 

Is there   something like 
       | 
       \s+ 

**如何匹配字符串

Is there   something like 
| 
\s* #matches here. Because there is zero occurence of space (Before the character I) 

Is there   something like 
| 
\s* # matches here as well and so on in all the characters 

    # Here it doesnt match any character, Rather it matches the postion between I and s as there is zero occurence of \s 

Answer 2

`*` matches an empty string as well. 

因此在Ne之間有一個空字符串。所以它會被空格替換。

Answer 3

*是零個或更多次數，零表示空

+是一個或多個Ocuurance，它匹配至少一個