How can I read X lines down from another line in a text file?

Question

I have a text file that I load into a string array. The contents of the file looks something like this:

OTI*IA*IX*NA~
REF*G1*J EVERETTE~
REF*11*0113722462~
AMT*GW*229.8~
NM1*QC*1*JENNINGS*PHILLIP~
OTI*IA*IX*NA~
REF*G1*J EVERETTE~
REF*11*0113722463~
AMT*GW*127.75~
NM1*QC*1*JENNINGS*PHILLIP~
OTI*IA*IX*NA~
REF*G1*J EVERETTE~
REF*11*0113722462~
AMT*GW*10.99~
NM1*QC*1*JENNINGS*PHILLIP~
...

I'm looking for the lines that start with OTI, and if it's followed by "IA" then I need to get the 10 digit number from the line that starts with REF*11. So far, I have this:

string[] readText = File.ReadAllLines("myfile.txt");

foreach (string s in readText) //string contains 1 line of text from above example
{
    string[] currentline = s.Split('*');

    if (currentline[0] == "OTI")
    {
        //move down 2 lines and grab the 10 digit
        //number from the line that starts with REF*11
    }
}

The line I need is always 2 lines after the current OTI line. How do I access the line that's 2 lines down from my current line?

Answer 1

Instead of using foreach() you can use a for(int index = 0; index < readText.Length; index++) Then you know the line you are accessing and you can easily say int otherIndex = index + 2

string[] readText = File.ReadAllLines("myfile.txt");

for(int index = 0; index < readText.Length; index++)
{
    string[] currentline = readText[index].Split('*');

    if (currentline[0] == "OTI")
    {
        //move down 2 lines and grab the 10 digit
        //number from the line that starts with REF*11
        int refIndex = index + 2;
        string refLine = readText[refIndex];
    }
}