How to Write Data Into a CSV File in C#

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Minahil Noor Feb 02, 2024
Csharp Csharp CSV
  1. C# Program to Write Data Into a CSV File Using CsvHelper Class Methods
  2. C# Program to Write Data Into a CSV File Using WriteAllText() Method
How to Write Data Into a CSV File in C#

CSV files are of great use in storing data in an organized way. You can write and read data to and from a CSV file using different programming languages.

In C# we have different methods for reading a CSV file and writing the data to a CSV file. This article focusses on the different methods to write data into a CSV file.

C# Program to Write Data Into a CSV File Using CsvHelper Class Methods

In C#, we have a library named CsvHelper for reading and writing CSV files. This library is not provided by default. Rather, we have to download it. It provides methods like GetRecords and WriteRecords to read and write a CSV file. This is an efficient library to read and write CSV files easily.

The following example code shows a program that creates a CSV file and writes data into it.

Example Code:

using System;
using System.IO;
using System.Text;
using CsvHelper;

namespace CsvExample {
  public class Project {
    public string PersonName { get; set; }
    public string Title { get; set; }
  }

  public class Program {
    static void Main(string[] args) {
      var data = new[] { new Project { CustomerName = "Olivia", Title = "Mother" },
                         new Project { CustomerName = "Lili", Title = "Elder Sister" } };

      using (var mem = new MemoryStream()) using (var writer = new StreamWriter(mem)) using (
          var csvWriter = new CsvWriter(writer)) {
        csvWriter.Configuration.Delimiter = ";";
        csvWriter.Configuration.HasHeaderRecord = true;
        csvWriter.Configuration.AutoMap<Project>();

        csvWriter.WriteHeader<Project>();
        csvWriter.WriteRecords(data);

        writer.Flush();
        var result = Encoding.UTF8.GetString(mem.ToArray());
        Console.WriteLine(result);
      }
    }
  }
}

Output:

PersonName;Title
Olivia;Mother
Lili;Elder Sister

C# Program to Write Data Into a CSV File Using WriteAllText() Method

The method WriteAllText() creates a file, writes data into the file and then closes the file. If the file already exists then it overwrites data in the file.

The correct syntax to use this method is as follows:

WriteAllText(StringPath, StringContents);

Example Code:

using System;
using System.IO;
using System.Text;

namespace CsvExample {

  public class Program {
    static void Main(string[] args) {
      string strFilePath = @"D:\New folder\Data.csv";
      string strSeperator = ",";
      StringBuilder sbOutput = new StringBuilder();

      int[][] inaOutput = new int[][] { new int[] { 1000, 2000, 3000, 4000, 5000 },
                                        new int[] { 6000, 7000, 8000, 9000, 10000 },
                                        new int[] { 11000, 12000, 13000, 14000, 15000 } };

      int ilength = inaOutput.GetLength(0);
      for (int i = 0; i & amp; lt; ilength; i++)
        sbOutput.AppendLine(string.Join(strSeperator, inaOutput[i]));

      // Create and write the csv file
      File.WriteAllText(strFilePath, sbOutput.ToString());

      // To append more lines to the csv file
      File.AppendAllText(strFilePath, sbOutput.ToString());
    }
  }
}

Output:

//CSV file created in the given directory

It gives several exceptions like ArgumentException, ArgumentNullException, PathTooLongException, DirectoryNotFoundException, IOException and UnauthorizedAccessException. These exceptions could be handled using a try-catch block.

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