c# Replace header text in CSV

Question

I have a csv file as shown below

I want to replace the text in the header. Aim is to replace _ underscores by a space.

Sample output

The Code I was trying was by using TextFieldParser

private void CSV_Operation(string path)
{
    using (TextFieldParser parser = new TextFieldParser(path))
    {
        // set the parser variables
        parser.TextFieldType = FieldType.Delimited;
        parser.SetDelimiters(",");

        bool firstLine = true;

        while (!parser.EndOfData)
        {
            string[] fields = parser.ReadFields();
            if (firstLine && fields != null)
            {
                //Code to replace this in actual .csv file, below code does not save these changes in the original file
                for (int i = 0; i < fields.Count(); i++)
                {
                    fields[i] = fields[i].Replace('_', ' ');
                }
            }

            // get the column headers
            if (firstLine)
            {
                firstLine = false;
            }
        }
    }
}

I want to persist the changes done to the header text in the original file. Any help?

I've removed the [asp.net] and [console-application] tags from your question because it's not clear how they relate to your specific question. If they are relevant, please edit your question to saw how. — ProgrammingLlama
– ProgrammingLlama, Commented Sep 7, 2020 at 12:40
Your first problem is using TextFieldParser in an ASP application. TextFieldParser is from the VisualBasic assembly, which you should avoid using. — Kilazur
– Kilazur, Commented Sep 7, 2020 at 12:40

Dmitrii Bychenko · Accepted Answer · 2020-09-07 12:53:25Z

2

If you want to change columns' heads (i.e. 1st line) only, while keeping csv body intact you can try

using System.IO;
using System.Linq;

...

private void CSV_Operation(string path) {
  var file = File
    .ReadLines(path)
    .SkipWhile(line => string.IsNullOrWhiteSpace(line)) // To be on the safe side
    .Select((line, index) => index == 0 // do we have header? 
       ? line.Replace('_', ' ') // replace '_' with ' '
       : line)                  // keep lines as they are 
    .ToList();                  // Materialization, since we write into the same file

  File.WriteAllLines(path, file);
}

answered Sep 7, 2020 at 12:53

Dmitrii Bychenko

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Comments

apomene · Accepted Answer · 2020-09-07 12:50:13Z

0

A quick alternative could be:

private void CSV_Operation(string path)
{
   File.WriteAllLines(path,  
                      File.ReadAllText(path).Replace('_', ' '),       
                      Encoding.UTF8);
}

edited Sep 7, 2020 at 12:50

answered Sep 7, 2020 at 12:44

apomene

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2 Comments

Dmitrii Bychenko Over a year ago

ReadAllText instead of ReadAllLines?

Sami Kuhmonen Over a year ago

But this will change all underscores, not just the header

VDWWD · Accepted Answer · 2020-09-07 12:56:01Z

0

You could do something like this

//read all the lines but skip the first
var lines = File.ReadLines(Server.MapPath("/test.csv")).Skip(1).ToList();

//create a new header if you want more than just remove the _
string newHeader = "ID;Name;Address;Contact";

//merge both
string newCsv = string.Format("{0}\r\n{1}", newHeader, string.Join("\r\n", lines));

answered Sep 7, 2020 at 12:56

VDWWD

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