C#: What's an effecient way of parsing a string with one delimiter through ReadLine() of TextReader?

Question

C#: What's an effecient way to parse a string with one delimiter for each ReadLine() of TextReader?

My objective is to load a list of proxies to ListView into two columns (Proxy|Port) reading from a .txt file. How would I go upon splitting each readline() into the proxy and port variables with the delimiter ":"?

This is what I've got so far,

    public void loadProxies(string FilePath)
    {
        string Proxy; // example/temporary place holders
        int Port; // updated at each readline() loop.

        using (TextReader textReader = new StreamReader(FilePath))
        {
            string Line;
            while ((Line = textReader.ReadLine()) != null)
            {
                // How would I go about directing which string to return whether
                // what's to the left of the delimiter : or to the right?
                //Proxy = Line.Split(':');
                //Port = Line.Split(':');

                // listview stuff done here (this part I'm familiar with already)
            }
        }
    }

If not, is there a more efficient way to do this?

Answer 1

You could split them this way:

        string line;
        string[] tokens;
        while ((Line = textReader.ReadLine()) != null)
        {
            tokens = line.Split(':');
            proxy = tokens[0];
            port = tokens[1];

            // listview stuff done here (this part I'm familiar with already)
        }

it's best practise to use small letter names for variables in C#, as the other ones are reserved for class / namespace names etc.

Answer 2

string [] parts = line.Split(':');
string proxy = parts[0];
string port = parts[1];

Answer 3

You might want to try something like this.

var items = File.ReadAllText(FilePath)
    .Split(new[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries)
    .Select(line => line.Split(':'))
    .Select(pieces => new { 
        Proxy = pieces[0], 
        Port = int.Parse(pieces[1]) 
    });

If you know that you won't have a stray newline at the end of the file you can do this.

var items = File.ReadAllLines(FilePath)
    .Select(line => line.Split(':'))
    .Select(pieces => new { 
        Proxy = pieces[0], 
        Port = Convert.ToInt32(pieces[1]) 
    });

Answer 4

How about running a Regex on the whole file?

var parts=
    Regex.Matches(input, @"(?<left>[^:]*):(?<right>.*)",RegexOptions.Multiline)
    .Cast<Match>()
    .Where(m=>m.Success)
    .Select(m => new
        {
            left = m.Groups["left"],
            right = m.Groups["right"]
        });

foreach(var part in parts)
{
    //part.left
    //part.right
}

Or, if it's too big, why not Linqify the ReadLine operation with yielding method?

static IEnumerable<string> Lines(string filename)
{
    using (var sr = new StreamReader(filename))
    {
        while (!sr.EndOfStream)
        {
            yield return sr.ReadLine();
        }
    }
}

And run it like so:

var parts=Lines(filename)
.Select(
    line=>Regex.Match(input, @"(?<left>[^:]*):(?<right>.*)")
)
.Where(m=>m.Success)
.Select(m => new
    {
        left = m.Groups["left"],
        right = m.Groups["right"]
    });
foreach(var part in parts)
{
    //part.left
    //part.right
}

Answer 5

In terms of efficiency I expect you'd be hard-pressed to beat:

    int index = line.IndexOf(':');
    if (index < 0) throw new InvalidOperationException();
    Proxy = line.Substring(0, index);
    Port = int.Parse(line.Substring(index + 1));

This avoids the array construction / allocation associated with Split, and only looks as far as the first delimited. But I should stress that this is unlikely to be a genuine performance bottleneck unless the data volume is huge, so pretty-much any approach should be fine. In fact, perhaps the most important thing (I've been reminded by the comment below) is to suspend the UI while adding:

myListView.BeginUpdate();
try {
    // TODO: add all the items here
} finally {
    myListView.EndUpdate();
}