如何改进正则表达式以消除不必要的方法链接? [英] How do I improve regex to eliminate unnecessary method chaining?

问题描述

此功能方法采用一个数字，并返回相同的值，以逗号分隔，这与美国的常见惯例相同.

This functional method takes a number and returns the same value separated with commas, as is the common convention in the US.

我可以使它与regex一起使用的唯一方法是在表达式前后反转字符串.是否有一个正则表达式可以帮助我消除两次调用String#reverse以实现方法功能的需要?

The only way I could get it to work with regex was to reverse the string before and after the expression. Is there a regex that can help me eliminate the need to call String#reverse twice for method functionality?

def separate_comma(number)
  raise "You must enter a number." if number.is_a?(Numeric) == false
  number.to_s.reverse.gsub(/(\d{3})(?=\d{1,3})/, "\\1,").reverse
end

推荐答案

"1234556".gsub(/\d(?=\d{3}+\b)/,'\\0,')
# => "1,234,556"

这不能处理长分数，但这也不是OP的正则表达式的问题.

This doesn't handle long fractional values, but this wasn't a concern for the OP's regex either.

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