Get wrong output

Question

My code is as follow
The output is null, I should use while loop as you see, but somewhere in my code is not working properly. and I'm not able to use any other library I need an hours array and rate array for employeeId==1 and the same for other employees(the CSV file is larger than what I pasted here)

public static List<PayRecord> ImportPayRecords(string file)
{
    List<PayRecord> payRecords = new List<PayRecord>();
    StreamReader reader = new StreamReader(file);
    int EmployeeId;
    int i = 0;
    int id;
    string Visa = "";
    string YearToDate = "";
    string record;
    string[] strArr;
    double[] Hours = new double[10];
    double[] Rate = new double[10];

    record = reader.ReadLine();
    strArr = record.Split(',');

    while (record != null)
    {
        EmployeeId = int.Parse(strArr[0]);

        if (strArr[3] != "")
        {
            Visa = strArr[3];
            YearToDate = strArr[4];
        }

        id = EmployeeId;

        while (record != null && id == int.Parse(strArr[0]))
        {
            Hours[i] = double.Parse(strArr[1]);
            Rate[i] = double.Parse(strArr[2]);
            i++;
            record = reader.ReadLine();

            if (record != null)
            {
                strArr = record.Split(',');
            }                   
        }

        PayRecord rec = CreatePayRecord(EmployeeId, Hours, Rate, Visa, YearToDate);                
        payRecords.Add(rec);
        double gross = rec.Gross;
        i = 0;
        Array.Clear(Hours, i, 10);
        Array.Clear(Rate, i, 10);
    }

    return payRecords;
}

the CSV file is like this:

EmployeeId,Hours,Rate,Visa,YearToDate

1,2,25,,
1,3,25,,
1,3,25,,
1,4,25,,
1,5,32,,
1,6,32,,
2,2,25,417,47520
2,2,25,417,47520
2,2,25,417,47520
2,2,25,417,47520
2,2,25,417,47520
2,2,28,417,47520
2,2,28,417,47520
2,2,28,417,47520

Answer 1

Although a CSV library will help with complex files, this file isn't so complex. To solve the immediate problem, add a ReadLine before reading the first record:

reader.ReadLine();
record = reader.ReadLine();

The code would become a lot easier to write, debug and test with a bit of cleanup. Instead of using a StreamReader like this, you can use File.ReadLines which returns an IEnumerable<string>. The result is the same as this code, only a lot easier to write. Once you have an IEnumerable<T> you can skip lines, parse lines etc :

int headerRows=1;
var lineRecords = File.ReadLines(file)
                     .Skip(headerRows)
                     .Select(line=>ParseLine(line,","))
                     .ToList()

Don't try to both parse records and analyze them in the same method.

Parsing the line and creating the pay record should be performed by a separate method. I'm using a C# record just so I don't have to write a class with explicit properties :

record LineRecord(int Id,double Hours,double Rate,string Visa,string YearToDate);

LineRecord ParseLine(string line,string separator)
{
    var fields=line.Split(separator);

    var id = int.Parse(fields[0]);
    var hours = double.Parse(fields[1]);
    var rate = double.Parse(fields[2])
    var visa = fields[3];
    var yearToDate = fields[4]

    return new LineRecord(id, hours, rate, visa, yearToDate); 
}

Even if you use a library like CsvHelper you'll end up at this point, with a list of parsed records.

After that, you can analyze and group the data any way you want using eg LINQ:

var byEmployee=lineRecords.GroupBy(rec=>rec.Id)
                          .Select(g=>new {
                              Id=g.Key,
                              Hours=g.Select(r=>r.Hours),ToArray(),
                              Rates=g.Select(r=>r.Rate).ToArray(),        
                              Visa =g.First(r=>r.Visa),
                              YearToDate = g.First(r=>r.YearToDate)
                          });

or

var payRecords=lineRecords.GroupBy(rec=>rec.Id)
                          .Select(g=> CreatePayRecord(
                              g.Key,
                              g.Select(r=>r.Hours),ToArray(),
                              g.Select(r=>r.Rate).ToArray(),        
                              g.First(r=>r.Visa),
                              g.First(r=>r.YearToDate)
                          ))
                          .ToList();

You could even combine both operations in a single LINQ query:

var payRecords = File.ReadLines(file)
                     .Skip(headerRows)
                     .Select(line=>ParseLine(line,","))
                     .GroupBy(rec=>rec.Id)
                     .Select(g=> CreatePayRecord(
                             g.Key,
                             g.Select(r=>r.Hours),ToArray(),
                             g.Select(r=>r.Rate).ToArray(),        
                             g.First(r=>r.Visa),
                             g.First(r=>r.YearToDate)
                      ))
                      .ToList();

Answer 2

Your code is not making it clear what you really want, with some guessing, you want a result like (displayed as JSON for easy representation):

[
  {
    "EmployeeId": 1,
    "Hours": [2.0,3.0,3.0,4.0,5.0,6.0],
    "Rate": [25.0,25.0,25.0,25.0,32.0,32.0],
    "Visa": "",
    "YearToDate": ""
  },
  {
    "EmployeeId": 2,
    "Hours": [2.0,2.0,2.0,2.0,2.0,2.0,2.0,2.0],
    "Rate": [25.0,25.0,25.0,25.0,25.0,28.0,28.0,28.0],
    "Visa": "417",
    "YearToDate": "47520"
  }
]

Right? Then:

public static List<PayRecord> ImportPayRecords(string file)
{
    return File.ReadAllLines(file)
    .Skip(1)
    .Select(f => f.Split(','))
    .Select(x => new {id=x[0], hour=x[1], rate=x[2],visa=x[3],ytd=x[4]})
    .GroupBy(x => x.id)
    .Select(x => new PayRecord {
        EmployeeId = int.Parse(x.Key),
        Hours = x.Select(y => double.Parse(y.hour)).ToArray(),
        Rate = x.Select(y => double.Parse(y.rate)).ToArray(),
        Visa = x.First().visa,
        YearToDate = x.First().ytd
    })
    .ToList();
}

BTW, there are ready made libraries like LinqToCSV to do this type of things easier.