Question

I have UK postcodes data and I would like to sort them alphabeticaly, when I do that the result is as follows;

N10-XX
N1-XX
N2-XX
N3-XX
N4-XX
N5-XX

What I want is that as follows;

N1-XX
N2-XX
N3-XX
N4-XX
N5-XX
N10-XX

Basicaly I need to add 0 at the begining of the number if it is 1 digit. like N1 should be N01 to be able to do that, what is the regexp pattern for that?

Many thanks.

Answer 1

Well if you are bent on using Regex, then this should do it

var text = @"N10-XX
N1-XX
N2-XX
N3-XX
N4-XX
N5-XX";

text = Regex.Replace(text, @"^N(\d)-", "N0$1-", RegexOptions.Multiline);

that said you obviously will be altering the original data, so I am not sure if this is even applicable

If you want to sort numerically, but preserve the original data, then you may need to do something like this

text.Split('\n')
    .Select(o => new { Original = o, Normal = Regex.Replace(o, @"^N(\d)-", "N0$1-", RegexOptions.Compiled)})
    .OrderBy(o => o.Normal)
    .Select(o => o.Original)