Question

I’ve got a text file full of records where each field in each record is a fixed width. My first approach would be to parse each record simply using string.Substring(). Is there a better way?

For example, the format could be described as:

<Field1(8)><Field2(16)><Field3(12)> 

And an example file with two records could look like:

SomeData0000000000123456SomeMoreData Data2   0000000000555555MoreData     

I just want to make sure I’m not overlooking a more elegant way than Substring().

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Update: I ultimately went with a regex like Killersponge suggested:

private readonly Regex reLot = new Regex(REGEX_LOT, RegexOptions.Compiled); const string REGEX_LOT = '^(?<Field1>.{6})' +                         '(?<Field2>.{16})' +                         '(?<Field3>.{12})'; 

I then use the following to access the fields:

Match match = reLot.Match(record); string field1 = match.Groups['Field1'].Value; 

Answer 1

Substring sounds good to me. The only downside I can immediately think of is that it means copying the data each time, but I wouldn’t worry about that until you prove it’s a bottleneck. Substring is simple 🙂

You could use a regex to match a whole record at a time and capture the fields, but I think that would be overkill.