How do I extract a substring from a string until the second space is encountered?

Question

I have a string like this:

\"o1 1232.5467 1232.5467 1232.5467 1232.5467 1232.5467 1232.5467\"

How do I extract only \"o1 1232.5467\"?

Answer 1

A straightforward approach would be the following:

string[] tokens = str.Split(' ');
string retVal = tokens[0] + " " + tokens[1];

Answer 2

There are shorter ways of doing it like others have said, but you can also check each character until you encounter a second space yourself, then return the corresponding substring.

static string Extract(string str)
{
    bool end = false;
    int length = 0 ;
    foreach (char c in str)
    {
        if (c == ' ' && end == false)
        {
            end = true;
        }
        else if (c == ' ' && end == true)
        {
            break;
        }

        length++;
    }

    return str.Substring(0, length);
}

Answer 3

Get the position of the first space:

int space1 = theString.IndexOf(' ');

The the position of the next space after that:

int space2 = theString.IndexOf(' ', space1 + 1);

Get the part of the string up to the second space:

string firstPart = theString.Substring(0, space2);

The above code put togehter into a one-liner:

string firstPart = theString.Substring(0, theString.IndexOf(' ', theString.IndexOf(' ') + 1));

Answer 4

I would recommend a regular expression for this since it handles cases that you might not have considered.

var input = "o1 1232.5467 1232.5467 1232.5467 1232.5467 1232.5467 1232.5467";
var regex = new Regex(@"^(.*? .*?) ");
var match = regex.Match(input);
if (match.Success)
{
    Console.WriteLine(string.Format("'{0}'", match.Groups[1].Value));
}

Answer 5

I was thinking about this problem for my own code and even though I probably will end up using something simpler/faster, here's another Linq solution that's similar to one that @Francisco added.

I just like it because it reads the most like what you actually want to do: "Take chars while the resulting substring has fewer than 2 spaces."

string input = "o1 1232.5467 1232.5467 1232.5467 1232.5467 1232.5467 1232.5467";
var substring = input.TakeWhile((c0, index) => 
                                input.Substring(0, index + 1).Count(c => c == ' ') < 2);
string result = new String(substring.ToArray());

Answer 6

s.Substring(0, s.IndexOf(" ", s.IndexOf(" ") + 1))