Member Avatar for yamid

How to read a part of a text file and put them in an array in c#
0 #1 1 Day Ago
I have a text file including several strings and doubles. I want to find a specific string in the text and read all double numbers after it which are located between two slashes"/". The number of double data could be unknown-but we just know they are bounded with two slashes- the file is two big and including several strings for example my data file is like this and I want to put all Double numbers,bounded between slashes and after "POROSITY" into an array with name "POROSITY".
*****************************************************
Permeability
/
1 2 3 4
5 6 7 8
9 10
11 12 13 14
15 15 17 18
19 20
21 22 23 24
25 26 27 28
29 30
.
.
.
/
POROSITY
/
1 2 3 4
5 6 7 8
9 10
11 12 13 14
15 15 17 18
19 20
21 22 23 24
25 26 27 28
29 30
.
.
.
/

  • 3 Contributors
  • 2 Replies
  • 805 Views
  • 20 Hours Discussion Span
  • Latest Post Latest Post by sknake

Dani AI

Generated

Brief summary and a robust alternative approach.

As recommended, treat the slash (/) lines as table delimiters and locate the header (POROSITY) first. 's working example shows a full implementation that builds a dictionary of named blocks. The following notes and sample show a streaming, regex-based alternative that avoids loading the entire file, tolerates stray whitespace (for example the sample has "/ "), and parses floating-point values reliably.

The approach

  • Stream the file line by line to keep memory usage low.
  • Find the header line (case-insensitive), skip to the next slash, then collect lines until the next slash is reached.
  • Use a regex to extract numeric tokens (handles integers, decimals and scientific notation).
  • Parse with CultureInfo.InvariantCulture and optionally fall back to the current culture if comma decimals are expected.
  • Stop after the first matching block or continue collecting if multiple blocks with the same name are required.

Example (streaming + regex, C#):

using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;

public static double[] ReadSectionNumbers(string path, string sectionName)
{
    using (var sr = new StreamReader(path))
    {
        string line;
        bool foundHeader = false, inBlock = false;
        var sb = new StringBuilder();
        while ((line = sr.ReadLine()) != null)
        {
            string t = line.Trim();
            if (!foundHeader)
            {
                if (string.Equals(t, sectionName, StringComparison.OrdinalIgnoreCase))
                    foundHeader = true;
            }
            else if (!inBlock)
            {
                if (t.StartsWith("/")) inBlock = true;
            }
            else
            {
                if (t.StartsWith("/")) break;
                sb.AppendLine(t);
            }
        }

        var matches = Regex.Matches(sb.ToString(), @"-?\d+(\.\d+)?([eE][+-]?\d+)?");
        var list = new List<double>(matches.Count);
        foreach (Match m in matches)
            if (double.TryParse(m.Value, NumberStyles.Float, CultureInfo.InvariantCulture, out double v) ||
                double.TryParse(m.Value, NumberStyles.Float, CultureInfo.CurrentCulture, out v))
                list.Add(v);
        return list.ToArray();
    }
}

Troubleshooting tips

  • Watch for trailing spaces on slash lines; use Trim or StartsWith("/") as above.
  • If the file is truly enormous and only one section is needed, the streaming version exits early and is efficient.
  • If numeric formatting includes commas as decimal separators, parse with the appropriate CultureInfo.
  • For malformed lines, log or skip tokens rather than throwing exceptions.

Recommended Answers

All 2 Replies

Member Avatar for ddanbe

Read file, when you read POROSITY read "/"
Then read all following chars until "/" into a string array.
Don't know with what chars your doubles are separated, but if you know, use the string.Split method to separate all doubles in an array.

Member Avatar for sknake 
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace daniweb
{
  public partial class frmDoubleRead : Form
  {
    public frmDoubleRead()
    {
      InitializeComponent();
    }

    private static string[] GetTestData()
    {
      List<string> result = new List<string>();
      result.Add("Permeability");
      result.Add("/");
      result.Add("1 2 3 4");
      result.Add("5 6 7 8");
      result.Add("9 10");
      result.Add("11 12 13 14");
      result.Add("15 15 17 18");
      result.Add("19 20");
      result.Add("21 22 23 24");
      result.Add("25 26 27 28");
      result.Add("29 30");
      result.Add(".");
      result.Add(".");
      result.Add(".");
      result.Add("/");
      result.Add("POROSITY");
      result.Add("/");
      result.Add("1 2 3 4");
      result.Add("5 6 7 8");
      result.Add("9 10");
      result.Add("11 12 13 14");
      result.Add("15 15 17 18");
      result.Add("19 20");
      result.Add("21 22 23 24");
      result.Add("25 26 27 28");
      result.Add("29 30");
      result.Add(".");
      result.Add(".");
      result.Add(".");
      result.Add("/ ");
      return result.ToArray();
    }

    private void button1_Click(object sender, EventArgs e)
    {
      Dictionary<string, List<int>> dict = new Dictionary<string, List<int>>(StringComparer.CurrentCultureIgnoreCase);

      const string TABLE_BEGIN = @"/";
      //string[] lines = System.IO.File.ReadAllLines(@"C:\data.txt");
      string[] lines = GetTestData();

      string curTable = string.Empty;
      List<int> curWorkingSet = null;

      for (int i1 = 0; i1 < lines.Length; i1++)
      {
        string trimmedLine = (string.IsNullOrEmpty(lines[i1]) ? string.Empty : lines[i1].Trim());
        if (trimmedLine.Equals(TABLE_BEGIN))
        {
          if (string.IsNullOrEmpty(curTable))
          {
            curTable = lines[i1 - 1];
            if (!dict.TryGetValue(curTable, out curWorkingSet))
            {
              curWorkingSet = new List<int>();
              dict.Add(curTable, curWorkingSet);
            }
          }
          else
            curTable = string.Empty;
        }
        string[] lineFields = trimmedLine.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
        foreach (string s in lineFields)
        {
          int i;
          if (int.TryParse(s, out i))
            curWorkingSet.Add(i);
        }
      }

      foreach (KeyValuePair<string, List<int>> kvp in dict)
      {
        string key = kvp.Key;
        int[] iValues = kvp.Value.ToArray();
        string[] sValues = Array.ConvertAll<int, string>(iValues, Convert.ToString);
        Console.WriteLine("{0}: {1}",
          key,
          string.Join(", ", sValues));
      }
    }

  }
}

Results in:

Permeability: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
POROSITY: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
commented: i would give my left nut to have your code library! :p +1
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