在換行後刪除多個空格

Question

我想刪除換行符後面的多個空格和製表符，以保留換行符。例如字符串：

str = "This is a really good morning\n    " 

我如何刪除多個空格"\n"後？

Answer 1

使用正則表達式（String#sub）：

str = "This is a really good morning\n    " 
str.sub(/[ \t]+\z/, '') # `[ \t]+\z` matches spaces, tabs at the end of the string. 
# => "This is a really good morning\n" 

如果你只想刪除多個空格（2個或更多）：

str.sub(/[ \t]{2,}\z/, '') 
# => "This is a really good morning\n" 

Answer 2

的問題是不明確的。以下是我承擔，但其他的解釋是可能的：

• 如果最後一個非空白字符是字符串的最後一個字符，返回字符串;

• 否則，如果最後一個非空白字符後面的空白不包含換行符（「\ n」），則去掉尾隨的空格;

• 否則將緊隨最後一個非空白字符的第一個換行符後面的尾隨空白字符去掉。

這些假設的一個結果是，任何非空白字符後面的換行符被視爲與非空白字符相同。

這一個來實現這些假設的方法：

def strip_it(str) 
    len = str.strip.size 
    i = str[len..-1].index("\n") 
    i ? str[0,len+i+1] : str.rstrip 
end 

一些例子：

strip_it "This is a really good morning\n    " 
    #=> "This is a really good morning\n" 

strip_it "This is a really good morning \n    " 
    #=> "This is a really good morning \n" 

strip_it "This is a really good morning" 
    #=> "This is a really good morning" 

strip_it "This is a really good morning\n cat  " 
    #=> "This is a really good morning\n cat" 

strip_it "This is a really good morning\n cat\n  " 
    #=> "This is a really good morning\n cat\n" 

strip_it "This is a really good morning\n cat \n  " 
    #=> "This is a really good morning\n cat \n" 

strip_it "This is a really good morning\n cat \n dog \n " 
    #=> "This is a really good morning\n cat \n dog \n" 

Lumina的，它可能看起來像I'm dancing on the head of a pin，但我走進一些細節的原因之一是顯示你爲什麼有必要精確地陳述假設和要求。在實際應用中，當需求不明確時，災難即將到來。