在换行后删除多个空格

Question

我想删除换行符后面的多个空格和制表符，以保留换行符。例如字符串：

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

我如何删除多个空格"\n"后？

Answer 1

使用正则表达式（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" 

如果你只想删除多个空格（2个或更多）：

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

Answer 2

的问题是不明确的。以下是我承担，但其他的解释是可能的：

• 如果最后一个非空白字符是字符串的最后一个字符，返回字符串;

• 否则，如果最后一个非空白字符后面的空白不包含换行符（“\ n”），则去掉尾随的空格;

• 否则将紧随最后一个非空白字符的第一个换行符后面的尾随空白字符去掉。

这些假设的一个结果是，任何非空白字符后面的换行符被视为与非空白字符相同。

这一个来实现这些假设的方法：

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，它可能看起来像I'm dancing on the head of a pin，但我走进一些细节的原因之一是显示你为什么有必要精确地陈述假设和要求。在实际应用中，当需求不明确时，灾难即将到来。