如何从文本文件中的另一行读取X行？

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];
    }
}

Answer 2

This looks like an EDI file! Ahh, EDI, the memories...

The good news is that the EDI file is delimited, just like most CSV file formats. You can use any standard CSV file library to load the EDI file into a gigantic array, and then iterate through it by position.

I published my open source CSV library here, feel free to use it if it's helpful. You can simply specify the "asterisk" as the delimiter:

https://code.google.com/p/csharp-csv-reader/

// This code assumes the file is on disk, and the first row of the file
// has the names of the columns on it
DataTable dt = CSVReader.LoadDataTable(myfilename, '*', '\"');

At this point, you can iterate through the datatable as normal.

for (int i = 0; i < dt.Rows.Count; i++) {
    if (dt.Rows[i][0] == "OTI") {
        Console.WriteLine("The row I want is: " + dt.Rows[i + 2][0]);
    }
}

Answer 3

What about:

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

for (int i = 0; i < readText.Length; i++)
{
    if (readText[i].StartsWith("OTI") && readText[i+2].StartsWith("REF*11")){
       string number = readText[i+2].Substring("REF*11".Length, 10);
       //do something 
    }
}

Answer 4

If you want to use regex to tokenize the items and create dynamic entities, here is such a pattern

string data = @"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~";

string pattern = @"^(?<Command>\w{3})((?:\*)(?<Value>[^~*]+))+";

var lines = Regex.Matches(data, pattern, RegexOptions.Multiline)
                 .OfType<Match>()
                 .Select (mt => new
                 {
                    Op   = mt.Groups["Command"].Value,
                    Data = mt.Groups["Value"].Captures.OfType<Capture>().Select (c => c.Value)
                 }
                 );

That produces a list of items like this which you can apply your business logic to:

Answer 5

Why dont you use regular expression matches using Regex.Match or Regex.Matches defined in System.Text.RegularExpressions? You can also look at string pattern matching algorithms such as the Knuth-Morris-Pratt algorithms.

Answer 6

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] == "REF"&&currentline[1] == "11")
    {
        found=false;
        needed=current+2;
    }
}

Answer 7

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

for(int linenum = 0;linenum < readText.Length; linenum++) 
{
    string s = readText[linenum];

    string[] currentline = s.Split('*');

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

        // Extract your number here from refline

    }  
}

Answer 8

Thank guys .. this is what I came up with, but I'm also reading your answers as I KNOW I will learn something! Thanks again!

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

int i = 0;
foreach (string s in readText)
{
    string[] currentline = s.Split('*');

    if (currentline[0] == "OTI")
    {
        lbRecon.Items.Add(readText[i+2].Substring(8, 9));
    }
i++;
}