String.Split only on first separator in C#?

String.Split is convenient for splitting a string with in multiple part on a delimiter.

How should I go on splitting a string only on the first delimiter. E.g. I've a String

"Time: 10:12:12\r\n"

And I'd want an array looking like

{"Time","10:12:12\r\n"}

The best approach depends a little on how flexible you want the parsing to be, with regard to possible extra spaces and such. Check the exact format specifications to see what you need.

yourString.Split(new char[] { ':' }, 2)

Will limit you two 2 substrings. However, this does not trim the space at the beginning of the second string. You could do that in a second operation after the split however.

yourString.Split(new char[] { ':', ' ' }, 2,
    StringSplitOptions.RemoveEmptyEntries)

Should work, but will break if you're trying to split a header name that contains a space.

yourString.Split(new string[] { ": " }, 2,
    StringSplitOptions.None);

Will do exactly what you describe, but actually requires the space to be present.

yourString.Split(new string[] { ": ", ":" }, 2,
    StringSplitOptions.None);

Makes the space optional, but you'd still have to TrimStart() in case of more than one space.

To keep the format somewhat flexible, and your code readable, I suggest using the first option:

string[] split = yourString.Split(new char[] { ':' }, 2);
// Optionally check split.Length here
split[1] = split[1].TrimStart();

In your example above you could split on ": " (i.e. colon with trailing space) as this appears to be what you've done. If you really did split on just the first delimeter you'd see a leading space in your second array element.

However, you should probably look at this overload of Split...

http://msdn.microsoft.com/en-us/library/c1bs0eda.aspx

public string[] Split(
  char[] separator,
  int count
)

... which allows you to specify a max number of substrings.

?("Time: 10:12:12\r\n").Split(new char[] { ':', ' ' }, 2, 
   StringSplitOptions.RemoveEmptyEntries)
{Dimensions:[2]}
    [0]: "Time"
    [1]: "10:12:12\r\n"

other options:

?("Time: 10:12:12\r\n").Split(new char[] { ':' }, 2)
{Dimensions:[2]}
    [0]: "Time"
    [1]: " 10:12:12\r\n"
?("Time: 10:12:12\r\n").Split(new char[] { ':' }, 1)
{Dimensions:[1]}
    [0]: "Time: 10:12:12\r\n"
?("Time: 10:12:12\r\n").Split(new char[] { ':' }, 3)
{Dimensions:[3]}
    [0]: "Time"
    [1]: " 10"
    [2]: "12:12\r\n"

I've adopted a variation to Thorarin's answer above, The below should be able to handle your requirement, plus trim the spaces.

yourString.Split(new []{'-'},2).Select(s => s.Trim())