C# || How To Parse A Delimited CSV File Using C#

May 14, 2021 admin No comments

The following is a module with functions which demonstrates how to parse a delimited CSV file using VB.NET.

This function parses a CSV file and returns its results as a List. Each List index represents a line in the CSV file, with each item in the list representing a record contained on that line.

The function demonstrated on this page uses FileIO.TextFieldParser to parse values in a CSV file.

Note: To use the function in this module, make sure you have a reference to ‘Microsoft.VisualBasic‘ in your project.

One way to do this is, in your Solution Explorer (where all the files are shown with your project), right click the ‘References‘ folder, click ‘Add Reference‘, then type ‘Microsoft.VisualBasic‘ in the search box, and add the reference titled Microsoft.VisualBasic in the results Tab.

1. Parse CSV File

The example below demonstrates the use of ‘Utils.Methods.ParseCsv‘ to parse a CSV file and return its results as a List.

The optional function parameter allows you to specify the delimiters. Default delimiter is a comma (,).

Sample CSV used in this example is the following:





		
		
			Kenneth,Perkins,120 jefferson st.,Riverside, NJ, 08075
Jack,McGinnis,220 hobo Av.,Phila, PA,09119
"Jennifer ""Da Man""",Repici,120 Jefferson St.,Riverside, NJ,08075
Stephen,Tyler,"7452 Terrace ""At the Plaza"" road",SomeTown,SD, 91234
,Blankman,,SomeTown, SD, 00298
"Joan ""the bone"", Anne",Jet,"9th, at Terrace plc",Desert City,CO,00123
			
				
					
				
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						Kenneth,Perkins,120 jefferson st.,Riverside, NJ, 08075
Jack,McGinnis,220 hobo Av.,Phila, PA,09119
"Jennifer ""Da Man""",Repici,120 Jefferson St.,Riverside, NJ,08075
Stephen,Tyler,"7452 Terrace ""At the Plaza"" road",SomeTown,SD, 91234
,Blankman,,SomeTown, SD, 00298
"Joan ""the bone"", Anne",Jet,"9th, at Terrace plc",Desert City,CO,00123





		
		
			1. Parse CSV File
			
C#
			
			// Parse CSV File

// Read file into byte array
byte[] fileBytes;

// Parse the contents of the file into a list
var fileContents = Utils.Methods.ParseCsv(fileBytes);

// Display the contents of the file
for (var lineIndex = 0; lineIndex < fileContents.Count; ++lineIndex) {
    var line = fileContents[lineIndex];

    Console.WriteLine($"Line #{lineIndex + 1}");
    foreach (var item in line) { 
        Console.WriteLine($"  Item: {item}");
    }
}

// expected output:
/*
    Line #1
      Item: Kenneth
      Item: Perkins
      Item: 120 jefferson st.
      Item: Riverside
      Item: NJ
      Item: 08075
    Line #2
      Item: Jack
      Item: McGinnis
      Item: 220 hobo Av.
      Item: Phila
      Item: PA
      Item: 09119
    Line #3
      Item: Jennifer "Da Man"
      Item: Repici
      Item: 120 Jefferson St.
      Item: Riverside
      Item: NJ
      Item: 08075
    Line #4
      Item: Stephen
      Item: Tyler
      Item: 7452 Terrace "At the Plaza" road
      Item: SomeTown
      Item: SD
      Item: 91234
    Line #5
      Item: 
      Item: Blankman
      Item: 
      Item: SomeTown
      Item: SD
      Item: 00298
    Line #6
      Item: Joan "the bone", Anne
      Item: Jet
      Item: 9th, at Terrace plc
      Item: Desert City
      Item: CO
      Item: 00123
*/
			
				
					
				
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						// Parse CSV File
 
// Read file into byte array
byte[] fileBytes;
 
// Parse the contents of the file into a list
var fileContents = Utils.Methods.ParseCsv(fileBytes);
 
// Display the contents of the file
for (var lineIndex = 0; lineIndex < fileContents.Count; ++lineIndex) {
    var line = fileContents[lineIndex];
 
    Console.WriteLine($"Line #{lineIndex + 1}");
    foreach (var item in line) { 
        Console.WriteLine($"  Item: {item}");
    }
}
 
// expected output:
/*
    Line #1
      Item: Kenneth
      Item: Perkins
      Item: 120 jefferson st.
      Item: Riverside
      Item: NJ
      Item: 08075
    Line #2
      Item: Jack
      Item: McGinnis
      Item: 220 hobo Av.
      Item: Phila
      Item: PA
      Item: 09119
    Line #3
      Item: Jennifer "Da Man"
      Item: Repici
      Item: 120 Jefferson St.
      Item: Riverside
      Item: NJ
      Item: 08075
    Line #4
      Item: Stephen
      Item: Tyler
      Item: 7452 Terrace "At the Plaza" road
      Item: SomeTown
      Item: SD
      Item: 91234
    Line #5
      Item: 
      Item: Blankman
      Item: 
      Item: SomeTown
      Item: SD
      Item: 00298
    Line #6
      Item: Joan "the bone", Anne
      Item: Jet
      Item: 9th, at Terrace plc
      Item: Desert City
      Item: CO
      Item: 00123
*/

2. Utils Namespace

The following is the Utils Namespace. Include this in your project to start using!





		
		
			Utils Namespace
			
C#
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 14, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Utils.cs
//    Description: Handles general utility functions
// ============================================================================
using System;
using System.Linq;
using System.Collections.Generic;

namespace Utils {
    public static class Methods {
        /// <summary>
        /// Parses a Csv file and returns its results as a List.
        /// Each List index represents a line in the Csv file, with each
        /// item in the list representing a record contained on that line.
        /// </summary>
        /// <param name="fileBytes">The Csv file as a byte array</param>
        /// <param name="delimiters">The Csv data delimiter</param>
        /// <returns>The the file contents as a List</returns>
        public static List<List<string>> ParseCsv(byte[] fileBytes
                , string delimiters = ",") {
            var results = new List<List<string>>();
            using (var stream = new System.IO.MemoryStream(fileBytes)) {
                using (var parser = new Microsoft.VisualBasic.FileIO.TextFieldParser(stream)) {
                    parser.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited;
                    parser.Delimiters = delimiters.Select(letter => letter.ToString()).ToArray();
                    parser.HasFieldsEnclosedInQuotes = true;

                    // Parse each line in the file
                    while (!parser.EndOfData) {
                        var currentLine = parser.ReadFields();
                        results.Add(currentLine.ToList());
                    }
                }
            }
            return results;
        }
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 14, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Utils.cs
//    Description: Handles general utility functions
// ============================================================================
using System;
using System.Linq;
using System.Collections.Generic;
 
namespace Utils {
    public static class Methods {
        /// <summary>
        /// Parses a Csv file and returns its results as a List.
        /// Each List index represents a line in the Csv file, with each
        /// item in the list representing a record contained on that line.
        /// </summary>
        /// <param name="fileBytes">The Csv file as a byte array</param>
        /// <param name="delimiters">The Csv data delimiter</param>
        /// <returns>The the file contents as a List</returns>
        public static List<List<string>> ParseCsv(byte[] fileBytes
                , string delimiters = ",") {
            var results = new List<List<string>>();
            using (var stream = new System.IO.MemoryStream(fileBytes)) {
                using (var parser = new Microsoft.VisualBasic.FileIO.TextFieldParser(stream)) {
                    parser.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited;
                    parser.Delimiters = delimiters.Select(letter => letter.ToString()).ToArray();
                    parser.HasFieldsEnclosedInQuotes = true;
 
                    // Parse each line in the file
                    while (!parser.EndOfData) {
                        var currentLine = parser.ReadFields();
                        results.Add(currentLine.ToList());
                    }
                }
            }
            return results;
        }
    }
}// http://programmingnotes.org/

3. More Examples

Below are more examples demonstrating the use of the ‘Utils‘ Namespace. Don’t forget to include the module when running the examples!





		
		
			More Examples
			
C#
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 14, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Program.cs
//    Description: The following demonstrates the use of the Utils Namespace
// ============================================================================
using System;
using System.Diagnostics;
using System.Collections.Generic;

public class Program {
    static void Main(string[] args) {
        try {
            // Read file into byte array
            byte[] fileBytes;

            // Parse the contents of the file into a list
            var fileContents = Utils.Methods.ParseCsv(fileBytes);

            // Display the contents of the file
            for (var lineIndex = 0; lineIndex < fileContents.Count; ++lineIndex) {
                var line = fileContents[lineIndex];

                Display($"Line #{lineIndex + 1}");
                foreach (var item in line) { 
                    Display($"  Item: {item}");
                }
            }
        } catch (Exception ex) {
            Display(ex.ToString());
        } finally {
            Console.ReadLine();
        }
    }

    static void Display(string message) {
        Console.WriteLine(message);
        Debug.Print(message);
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 14, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Program.cs
//    Description: The following demonstrates the use of the Utils Namespace
// ============================================================================
using System;
using System.Diagnostics;
using System.Collections.Generic;
 
public class Program {
    static void Main(string[] args) {
        try {
            // Read file into byte array
            byte[] fileBytes;
 
            // Parse the contents of the file into a list
            var fileContents = Utils.Methods.ParseCsv(fileBytes);
 
            // Display the contents of the file
            for (var lineIndex = 0; lineIndex < fileContents.Count; ++lineIndex) {
                var line = fileContents[lineIndex];
 
                Display($"Line #{lineIndex + 1}");
                foreach (var item in line) { 
                    Display($"  Item: {item}");
                }
            }
        } catch (Exception ex) {
            Display(ex.ToString());
        } finally {
            Console.ReadLine();
        }
    }
 
    static void Display(string message) {
        Console.WriteLine(message);
        Debug.Print(message);
    }
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

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Posted in: C#, Console Tags: c-sharp, csv file

C# || How To Parse A Delimited CSV File Using C#

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