CSV string handling

Question

Typical way of creating a CSV string (pseudocode):

1. Create a CSV container object (like a StringBuilder in C#).
2. Loop through the strings you want to ad

Answer 1

Don't forget our old friend "for". It's not as nice-looking as foreach but it has the advantage of being able to start at the second element.

public string ReturnAsCSV(ContactList contactList)
{
    if (contactList == null || contactList.Count == 0)
        return string.Empty;

    StringBuilder sb = new StringBuilder(contactList[0].Name);

    for (int i = 1; i < contactList.Count; i++)
    {
        sb.Append(",");
        sb.Append(contactList[i].Name);
    }

    return sb.ToString();
}

You could also wrap the second Append in an "if" that tests whether the Name property contains a double-quote or a comma, and if so, escape them appropriately.

Answer 2

You could use LINQ to Objects:

string [] strings = contactList.Select(c => c.Name).ToArray();
string csv = string.Join(",", strings);

Obviously that could all be done in one line, but it's a bit clearer on two.

Answer 3

I like the idea of adding the comma by checking if the container is empty, but doesn't that mean more processing as it needs to check the length of the string on each occurrence?

You're prematurely optimizing, the performance hit would be negligible.

Answer 4

Why not use one of the open source CSV libraries out there?

I know it sounds like overkill for something that appears so simple, but as you can tell by the comments and code snippets, there's more than meets the eye. In addition to handling full CSV compliance, you'll eventually want to handle both reading and writing CSVs... and you may want file manipulation.

I've used Open CSV on one of my projects before (but there are plenty of others to choose from). It certainly made my life easier. ;)

Answer 5

You could instead add the comma as the first thing inside your foreach.

if (sb.Length > 0) sb.Append(",");

Answer 6

How about some trimming?

public string ReturnAsCSV(ContactList contactList)
{
    StringBuilder sb = new StringBuilder();

    foreach (Contact c in contactList)
    {
        sb.Append(c.Name + ",");
    }

    return sb.ToString().Trim(',');
}