CODEWITHSUNDEEP
c#stringsplitsubstring
RollerMobster
RollerMobster

Reputation: 984

Extracting a block of text after the last instance of a specific string

I have a text file from which I need to extract a block of text after the last instance of a specific string. To better ilustrate what is needed:

SpecificString#1:
 TextBlock#1
SpecificString#2:
 TextBlock#2
...
SpecificString#5:
 TextBlock#5

All specific strings are identical, and the number of instances can vary. So far I am able to extract all TextBlocks after the first instance of the specific string with the following code:

const string separator = "SpecificString";
var separatorIndex = myTextFileString.IndexOf(separator, StringComparison.CurrentCultureIgnoreCase);
var requiredTextBlock = myTextFileString.Substring(separatorIndex + separator.Length);

However I would like to grab only the last block of text (TextBlock#5 in this case). How can I achieve this?

Upvotes: 1

Views: 208

Answers (2)

Ndubuisi Jr
Ndubuisi Jr

Reputation: 511

Probably you should Read the text file differently. For instance:

string[] allLinesInText = File.ReadAllLines(path);

This returns each line in the text file as an array of string from which you can filter out the separators and index the blocks easily

const string separator = "SpecificString";
var allLines=allLinesInText.Where(x=>!x.Contains(separator));

If the text file contains a single string, you have to try the other answers proposed.

Upvotes: 1

Abhijit Pal
Abhijit Pal

Reputation: 44

You can get the last index of the separator in C# by using String.LastIndexOf() method. Please take a look at https://learn.microsoft.com/en-us/dotnet/api/system.string.lastindexof?view=netframework-4.8.

Once you know the last index, you can follow the same step as you have mentioned above to extract the text block after it.

Upvotes: 1

Related Questions