Get Second Instance of Reading a Text File using StartsWith()

Question

I'm reading from a text file to find the Line Index where a certain line starts with my Criteria.
Turns out there are actually two instances of my desired criteria and I want to get the second one.
How would I amend the below code to Skip the first instance and get the second?

var linesB = File.ReadAllLines(In_EmailBody);
int LineNumberB = 0;
string criteriaB = "T:";
for (LineNumberB = 0; LineNumberB < linesB.Length; LineNumberB++){
    if(linesB[LineNumberB].StartsWith(criteriaB))
        break;
}

I use the result after and compare it to another criteria to find out the number of lines between the two results.

Answer 1

You could use following LINQ query to simplify your task:

List<string> twoMatchingLines = File.ReadLines(In_EmailBody)
    .Where(line = > line.StartsWith(criteriaB))
    .Take(2)
    .ToList();

Now you have both in the list.

string first = twoMatchingLines.ElementAtOrDefault(0);  // null if empty
string second = twoMatchingLines.ElementAtOrDefault(1); // null if empty or only one

---

If you want to use the for-loop(your last sentence suggests it), you could count the matching lines:

int matchCount = 0;
for (int i = 0; i < linesB.Length; i++)
{
    if(linesB[i].StartsWith(criteriaB) && ++matchCount == 2)
    {
        // here you are
    }
}