仅将字符串的第一个字符大写并留下其他字符？(导轨)

Question

我正在尝试让Rails将字符串的第一个字符大写,并将所有其他字符保留为字符串.我遇到了"我来自纽约"的问题变成了"我来自纽约".

我会用什么方法来选择第一个字符？

谢谢

编辑:我试图实现macek建议的,但我得到一个"未定义的方法`大写'"错误.没有大写行,代码工作正常.谢谢您的帮助!

def fixlistname!
  self.title = self.title.lstrip + (title.ends_with?("...") ? "" : "...")
  self.title[0] = self.title[0].capitalize
  errors.add_to_base("Title must start with \"You know you...\"") unless self.title.starts_with? 'You know you'
end

编辑2:搞定了.谢谢您的帮助!

编辑3:等等,不,我没有......这就是我的列表模型中的内容.

def fixlistname!
  self.title = self.title.lstrip + (title.ends_with?("...") ? "" : "...")
  self.title.slice(0,1).capitalize + self.title.slice(1..-1)
  errors.add_to_base("Title must start with \"You know you...\"") unless self.title.starts_with?  'You know you'
end

编辑4:尝试了macek的编辑,仍然得到一个未定义的方法"大写"错误.我可能做错了什么？

def fixlistname!
  self.title = title.lstrip
  self.title += '...' unless title.ends_with?('...')
  self.title[0] = title[0].capitalize
  errors.add_to_base('Title must start with "You know you..."') unless title.starts_with?("You know you")
end

编辑5:这很奇怪.我可以通过使用下面的行来摆脱未定义的方法错误.问题是它似乎用数字替换了第一个字母.例如,而不是资本的Ÿ在你,它把Ÿ为121

self.title[0] = title[0].to_s.capitalize

Answer 1

这应该这样做:

title = "test test"     
title[0] = title[0].capitalize
puts title # "Test test"

Answer 2

Titleize将把每个单词都化.这条线感觉很大,但会保证唯一的字母改变是第一个.

new_string = string.slice(0,1).capitalize + string.slice(1..-1)

更新:

irb(main):001:0> string = "i'm from New York..."
=> "i'm from New York..."
irb(main):002:0> new_string = string.slice(0,1).capitalize + string.slice(1..-1)
=> "I'm from New York..."

Answer 3

你可以使用人性化.如果您的文本行中不需要下划线或其他大写字母.

输入:

"i'm from New_York...".humanize

输出:

"I'm from new york..."

Answer 4

str = "this is a Test"
str.sub(/^./, &:upcase)
# => "This is a Test"

Answer 5

从Rails 5.0.0.beta4开始,您可以使用新String#upcase_first方法或ActiveSupport::Inflector#upcase_first执行此操作.查看此博客文章了解更多信息.

Answer 6

面向对象的解决方案:

class String
  def capitalize_first_char
    self.sub(/^(.)/) { $1.capitalize }
  end
end

然后你可以这样做:

"i'm from New York".capitalize_first_char

Answer 7

str.sub(/./, &:capitalize)

Answer 8

编辑2

我似乎无法复制你的麻烦.继续运行这个本机Ruby脚本.它生成您正在寻找的确切输出,Rails支持所有这些方法.您遇到什么问题？

#!/usr/bin/ruby
def fixlistname(title)
  title = title.lstrip
  title += '...' unless title =~ /\.{3}$/
  title[0] = title[0].capitalize
  raise 'Title must start with "You know you..."' unless title =~ /^You know you/
  title
end

DATA.each do |title|
  puts fixlistname(title)
end

__END__
you know you something WITH dots ...
you know you something WITHOUT the dots
  you know you something with LEADING whitespace...
  you know you something with whitespace BUT NO DOTS
this generates error because it doesn't start with you know you

产量

You know you something WITH dots ...
You know you something WITHOUT the dots...
You know you something with LEADING whitespace...
You know you something with whitespace BUT NO DOTS...
RuntimeError: Title must start with "You know you..."

编辑

根据您的编辑,您可以尝试这样的事情.

def fixlistname!
  self.title = title.lstrip
  self.title += '...' unless title.ends_with?('...')
  self.title[0] = title[0].capitalize
  errors.add_to_base('Title must start with "You know you..."') unless title.starts_with?("You know you")
end

原版的

这样就可以了

s = "i'm from New York"
s[0] = s[0].capitalize
#=> I'm from New York

在尝试使用String#capitalize整个字符串时,您看到的I'm from new york是因为该方法:

返回str的副本,第一个字符转换为大写,余数为小写.

"hello".capitalize    #=> "Hello"
"HELLO".capitalize    #=> "Hello"
"123ABC".capitalize   #=> "123abc"

Answer 9

my_string = "hello, World"
my_string.sub(/\S/, &:upcase) # => "Hello, World"