Extract specific lines from text file

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I have a structured text file which contains customer information here iz a few sample data
236,Janet, Stones,26300,19/10/2010
203,Linda,Phiri,15000,23/10/2010
150,Harry,Banda,16700,09/08/2010
418,Bridget, Tatianna,16/09/2010
210,Joseph,Alonzo,2900,23/10/2010
from this text file i wish to extract lines which contain a specific date so for example I want to extract all the lines containing '23/10/2010'
so i wrote the following code

static void main(string[] args)
{
  string path = @"C:\customers.txt";
  StringBuilder buffer = new StringBuilder();
  using (StreamReader = new StreamReader(path)){
  while(sr.Peek() >=0){
  if(Regex.IsMatch(sr.Readline(), "23/10/2010"))
  buffer.Append(sr.ReadLine());

}
}
Console.WriteLine(buffer.ToString());
}

when i run this instead of getting two lines i get only one whats even more strange is it only output the second line and not the first line so my result in this case is 210,Joseph,Alonzo,2900,23/10/2010 and if only 1 occurence had 23/10/2010 in the line then im getting empty results so I really need help with this one! Thanks

Posted 25-Oct-10 14:40pm

2gizzo

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4 solutions

Solution 5

Instead of suggesting alternate ways of accomplishing the task I focussed on why your code isn't working.

I work with C++, not C# but its a simple matter to see whats wrong by debugging the code. The changes are trivial and I won't mention them here; just the working code is pasted here.

To separate lines in the output I tried the C escape sequence "\r" and "\n" but I guess C# uses some different method.

C#

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {


            string path = @"h:\customers.txt";
            StringBuilder buffer = new StringBuilder();
            using (StreamReader sr = new StreamReader(path))
            {
                while(sr.Peek() >=0) {
                    String str = sr.ReadLine();
                    if(Regex.IsMatch(str, "23/10/2010"))
                        buffer.Append(str + @"\n");
                }
            }
            Console.WriteLine(buffer.ToString());
        }
    }
}

Posted 25-Oct-10 19:57pm

mahendra.kumar.786

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Nish Nishant · Accepted Answer · 2010-10-25T14:55:00

This is fairly simple, so you don't need to use regular expressions. Something like this would be easier:

C#

string[] lines = File.ReadAllLines(filePath);

IEnumerable<string> selectLines = lines.Where(line => line.EndsWith("23/10/2010"));

foreach (var item in selectLines)
{
    Console.WriteLine(item);
}

Karthik. A · Accepted Answer · 2010-10-25T18:41:00

You could use

String.Contains link[^]

or

String.IndexOf link[^] - IndexOf should return >= 0 for the line to contain the string you are searching for

instead of Regex matching, simple and straight-forward

C#

string stringToSearch = @"<your_string>";
string[] lines = File.ReadAllLines(@"path_to_your_file");
foreach (string line in lines)
{
    if (line.Contains(stringToSearch))
    {
    Console.WriteLine(line);
    }
}

or

C#

string stringToSearch = @"<your_string>";
string[] lines = File.ReadAllLines(@"path_to_your_file");
foreach (string line in lines)
{
    if (line.IndexOf(stringToSearch) >= 0)
    {
    Console.WriteLine(line);
    }
}

Heinzzy · Accepted Answer · 2010-10-25T19:00:00

I composed lines myself but you should read from your file

C#

string[] lines = {"236,Janet, Stones,26300,19/10/2010",
                             "203,Linda,Phiri,15000,23/10/2010",
                             "150,Harry,Banda,16700,19/10/2010",
                             "418,Bridget, Tatianna,16/09/2010",
                             "210,Joseph,Alonzo,2900,19/10/2010"};
           string date = @"19/10/2010";
           string pattern = @"((\w|\s)*,){3,4}"+date;
           foreach(string str in lines)
           {
               Console.WriteLine(Regex.Match(str,pattern ).Value.ToString());
           }

Extract specific lines from text file

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Extract specific lines from text file

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