Parsing CSV files in C#, with header

Question

Is there a default/official/recommended way to parse CSV files in C#? I don't want to roll my own parser.

Also, I've seen instances of people using ODBC/OLE DB to read CSV via the Text driver, and a lot of people discourage this due to its "drawbacks." What are these drawbacks?

Ideally, I'm looking for a way through which I can read the CSV by column name, using the first record as the header / field names. Some of the answers given are correct but work to basically deserialize the file into classes.

Answer 1

There's no official way I know of, but you should indeed use existing libraries. Here is one I found really useful from CodeProject:

http://www.codeproject.com/KB/database/CsvReader.aspx

Answer 2

Here is my KISS implementation...

using System;
using System.Collections.Generic;
using System.Text;

class CsvParser
{
    public static List<string> Parse(string line)
    {
        const char escapeChar = '"';
        const char splitChar = ',';
        bool inEscape = false;
        bool priorEscape = false;

        List<string> result = new List<string>();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < line.Length; i++)
        {
            char c = line[i];
            switch (c)
            {
                case escapeChar:
                    if (!inEscape)
                        inEscape = true;
                    else
                    {
                        if (!priorEscape)
                        {
                            if (i + 1 < line.Length && line[i + 1] == escapeChar)
                                priorEscape = true;
                            else
                                inEscape = false;
                        }
                        else
                        {
                            sb.Append(c);
                            priorEscape = false;
                        }
                    }
                    break;
                case splitChar:
                    if (inEscape) //if in escape
                        sb.Append(c);
                    else
                    {
                        result.Add(sb.ToString());
                        sb.Length = 0;
                    }
                    break;
                default:
                    sb.Append(c);
                    break;
            }
        }

        if (sb.Length > 0)
            result.Add(sb.ToString());

        return result;
    }

}

Answer 3

Let a library handle all the nitty-gritty details for you! :-)

Check out FileHelpers and stay DRY - Don't Repeat Yourself - no need to re-invent the wheel a gazillionth time....

You basically just need to define that shape of your data - the fields in your individual line in the CSV - by means of a public class (and so well-thought out attributes like default values, replacements for NULL values and so forth), point the FileHelpers engine at a file, and bingo - you get back all the entries from that file. One simple operation - great performance!

Answer 4

In a business application, i use the Open Source project on codeproject.com, CSVReader.

It works well, and has good performance. There is some benchmarking on the link i provided.

A simple example, copied from the project page:

using (CsvReader csv = new CsvReader(new StreamReader("data.csv"), true))
{
    int fieldCount = csv.FieldCount;
    string[] headers = csv.GetFieldHeaders();

    while (csv.ReadNextRecord())
    {
        for (int i = 0; i < fieldCount; i++)
            Console.Write(string.Format("{0} = {1};", headers[i], csv[i]));

        Console.WriteLine();
    }
}

As you can see, it's very easy to work with.

Answer 5

If you need only reading csv files then I recommend this library: A Fast CSV Reader
If you also need to generate csv files then use this one: FileHelpers

Both of them are free and opensource.

Answer 6

Based on unlimit's post on How to properly split a CSV using C# split() function? :

string[] tokens = System.Text.RegularExpressions.Regex.Split(paramString, ",");

NOTE: this doesn't handle escaped / nested commas, etc., and therefore is only suitable for certain simple CSV lists.