Ruby：如何使用正则表达式查看字符串是否为带破折号的日期格式？

Question

I want to see if the string I passed is in YYYY-MM-DD format.

string = "2013-03-02"
string[/\d{4}-\d{2}-\d{4}/] #why does it return nil?

I want to check that there are 4 digits, followed by a dash, followed by 2 digits, followed by a dash, followed by 2 digits.

Answer 1

\\d{4}-\\d{2}-\\d{4} should be \\d{4}-\\d{2}-\\d{2} as per your wish.

(arup~>~)$ pry --simple-prompt
>> string = "2013-03-02"
=> "2013-03-02"
>> string[/\d{4}-\d{2}-\d{2}/]
=> "2013-03-02"
>> string = "2013-03-2"
=> "2013-03-2"
>> string[/\d{4}-\d{2}-\d{2}/]
=> nil

Answer 2

irb(main):001:0> str = "2013-03-02"
=> "2013-03-02"
irb(main):002:0> str[/\d{4}-\d{2}-\d{2}/]
=> "2013-03-02"

Your last \\d{4} needs to be a \\d{2} . I love http://rubular.com/ for testing regex in Ruby.