Yesterday I wrote about regex that match string inside quotes and comma separated. Today, I was given task to process CSV file and upload it into DB. The CSV file is structured like this:

Column1,Column2,Column3
"Value 1",1, "This value contains
Newline"
"Value 2",2,"One line, and has comma"
"Value 3",3,"A short, but contains comma 
and new  line &ámp; HTML encoded "

I did wrote something about parsing CSV in C# and in JavaScript before. But both failed to handle above example.

Since I am not required to convert the string value to its actual data type, I can use a simple iteration to parse the CSV.

public List<List<string>> ReadCSVFileToList(StreamReader sr, char SeparatorChar)
{
    var res = new List<List<string>>();

    var curList = new List<string>();
    var curString = "";
    var isInQuote = false;
    while (!sr.EndOfStream)
    {
        var chr = (char)sr.Read();
        switch (chr)
        {
            case '"':
                isInQuote = !isInQuote;
                break;
            case '\n':
                if (isInQuote) curString += '\n';
                else
                {
                    curList.Add(curString);
                    curString = "";
                    res.Add(curList);
                    curList = new List<string>();
                }
                break;
            default:
                if (isInQuote)
                {
                    curString += chr;
                }
                else
                {
                    if (chr == SeparatorChar)
                    {
                        curList.Add(curString);
                        curString = "";
                    }
                    else
                        curString += chr;
                }
                break;
        }
    }
    return res;
}

I hope it helps!

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