CODEWITHSUNDEEP
c#parsing
user10111241
user10111241

Reputation:

C# Parsing a text file misses the first line of every text file

I am making a number to music note value converter from text files and I am having trouble parsing text files in my C# code. The stream reader or parser seems to ignore every first line of text from different text files, I am learning from parsing CSV and assumed that I can parse text files the same way that I can parse CSV files. Here is my code:

static List<NoteColumns> ReadNoteValues(string fileName)
    {
        var allNotes = new List<NoteColumns>();
        using (var reader = new StreamReader(fileName))
        {
            string line = "";
            reader.ReadLine();
            while ((line = reader.ReadLine()) != null)
            {
                string[] cols = line.Split('|');
                var noteColumn = new NoteColumns();
                if (line.StartsWith("-"))
                {
                    continue;
                }
                double col;
                if (double.TryParse(cols[0], out col))
                {
                    noteColumn.QCol = col;
                }
                if (double.TryParse(cols[1], out col))
                {
                    noteColumn.WCol = col;
                }
            }
        }
        return allNotes;
    }

Here are the first 4 lines of one of my text file:

0.1|0.0|
0.0|0.1|
0.3|0.0|
0.1|0.0|

So every time that I have an output it will always skip the first line and move onto the next line. After it misses the first line it converts all the other values perfectly.

I have tried using a foreach loop but I end up getting an 'Index Out Of Range Exception'. Am I missing something/being stupid? Thanks for your time

Upvotes: 1

Views: 278

Answers (3)

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186688

In order to avoid such errors (erroneous reader.ReadLine() in the beginning) get rid of Readers at all and query file with Linq (let .Net open and close the file, read it line after line and do all low level work for you):

using System.IO;
using System.Linq;

...  

static List<NoteColumns> ReadNoteValues(string fileName) {
  return File
    .ReadLines(fileName)
    .Where(line => !line.StartsWith('-'))
    .Select(line => line.Split('|'))
    .Select(cols => {
        var noteColumn = new NoteColumns();

        if (double.TryParse(cols[0], out var col))
          noteColumn.QCol = col;

        if (double.TryParse(cols[1], out var col))
          noteColumn.WCol = col;

        return noteColumn;  
     })
    .ToList();
}

Upvotes: 1

Ipsit Gaur
Ipsit Gaur

Reputation: 2927

It's because you have already added ReadLine() before the while loop which skips the first line

Upvotes: 4

johnny 5
johnny 5

Reputation: 20995

You have a call to reader.ReadLine(); before your loop, which you don't assign to anything

Upvotes: 4

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