格式化字符串的最快/最佳方法

Question

I know this may seem a junior question and it should have been easy to find the solution by Googling it but I am stuck.

I am using C#.

I have this string:

20150824100112345 (for instance)

I wish to transform it to a new string like so:

2015\\08\\24\\10\\00\\01\\12\\345

Is there a '1-liner' of code I can use to accomplish this please?

NB Without 1st converting it to a datetime format

Answer 1

As said in the comments, you should really parse it to a DateTime and then turn that into a string.

But to parse a string as you asked you should use a Regex which can split it into groups.

Answer 2

If you don't want to parse to DateTime first (ie if you don't care about validity) and if the input is always formatted as your example (zero-padded, so 08 instead of 8 ), you can do with a few simple Substring() calls:

string input = "20150824100112345";
string output = input.Substring(0, 4) + @"\" // 2015
              + input.Substring(4, 2) + @"\" // 08
              + input.Substring(6, 2) + @"\" // 24
              + input.Substring(8, 2) + @"\" // 10
              + input.Substring(10, 2) + @"\" // 01
              + input.Substring(12, 2) + @"\" // 12
              + input.Substring(14, 3); // 345

Or in Regex:

string input = "20150824100112345";
string output = Regex.Replace(input, 
                  "([0-9]{4})([0-9]{2})([0-9]{2})([0-9]{2})([0-9]{2})([0-9]{2})([0-9]{3})", 
                 @"$1\$2\$3\$4\$5\$6\$7");