Writing a CSV file in .net

CsvHelper (a library I maintain) also available via NuGet.

CsvHelper can automatically write your class objects to a file for you.

var myObj = new MyCustomClass
{
    Prop1 = "one",
    Prop2 = 2
};
var streamWriter = // Create a writer to somewhere...
var csvWriter = new CsvWriter( streamWriter );

// You can write a single record.
csvWriter.WriteRecord( myObj );

// You can also write a collection of records.
var myRecords = new List<MyCustomClass>{ myObj };
csvWriter.WriteRecords( myRecords );

If there are any commas in your cell, surround the entire cell with double quotes, eg:

cell 1,cell 2,"This is one cell, even with a comma",cell4,etc

And if you want a literal double quote, do two of them, eg:

cell 1,cell 2,"This is my cell and it has ""quotes"" in it",cell 4,etc

As for dates, stick to ISO format, and you should be fine (eg yyyy-mm-dd hh:mm:ss)

I would just like to add there's an RFC that specifies the CSV format which is what I would regard as the canonical source.

I've used filehelpers extensively and it's pretty awesome for generating CSVs.

Here is the function you can use to generate a row of CSV file from string list (IEnumerable(Of String) or string array can be used as well):

Function CreateCSVRow(strArray As List(Of String)) As String
    Dim csvCols As New List(Of String)
    Dim csvValue As String
    Dim needQuotes As Boolean
    For i As Integer = 0 To strArray.Count() - 1
        csvValue = strArray(i)
        needQuotes = (csvValue.IndexOf(",", StringComparison.InvariantCulture) >= 0 _
                      OrElse csvValue.IndexOf("""", StringComparison.InvariantCulture) >= 0 _
                      OrElse csvValue.IndexOf(vbCrLf, StringComparison.InvariantCulture) >= 0)
        csvValue = csvValue.Replace("""", """""")
        csvCols.Add(If(needQuotes, """" & csvValue & """", csvValue))
    Next
    Return String.Join(",", csvCols.ToArray())
End Function

As I think, it won't be difficult to convert from VB.NET to C#)