Question

I want to find a string in a txt file if string compares, it should go on reading lines till another string which I’m using as parameter.

Example:

CustomerEN //search for this string
...
some text which has details about the customer
id "123456"
username "rootuser"
...
CustomerCh //get text till this string

I need the details to work with them otherwise.

I’m using linq to search for "CustomerEN" like this:

File.ReadLines(pathToTextFile).Any(line => line.Contains("CustomerEN"))

But now I’m stuck with reading lines (data) till "CustomerCh" to extract details.

Answer 1

If your pair of lines will only appear once in your file, you could use

File.ReadLines(pathToTextFile)
    .SkipWhile(line => !line.Contains("CustomerEN"))
    .Skip(1) // optional
    .TakeWhile(line => !line.Contains("CustomerCh"));

If you could have multiple occurrences in one file, you’re probably better off using a regular foreach loop – reading lines, keeping track of whether you’re currently inside or outside a customer etc:

List<List<string>> groups = new List<List<string>>();
List<string> current = null;
foreach (var line in File.ReadAllLines(pathToFile))
{
    if (line.Contains("CustomerEN") && current == null)
        current = new List<string>();
    else if (line.Contains("CustomerCh") && current != null)
    {
        groups.Add(current);
        current = null;
    }
    if (current != null)
        current.Add(line);
}