Help me to split string using RegExp

Question

Hello, please help me this problem. I want to split "-action=1" to "action" and "1".

string pattern = @"^-(\S+)=(\S+)$";
Regex regex = new Regex(pattern);
string myText = "-action=1";
string[] result = regex.Split(myText);

I don't know why result have length=4.

result[0] = ""
result[1] = "action"
result[2] = "1"
result[3] = ""

Please help me.

P/S: I am using .NET 2.0.

Thanks.

Hello, I tested with string: @"-destination=C:\Program Files\Release" but it have inaccurate result, I don't understand why result's length = 1. I think because it has a white space in string.

I want to split it to "destination" & "C:\Program Files\Release"

More info: This is my requirement: -string1=string2 -> split it to: string1 & string2. In string1 & string2 don't contain characters: '-', '=', but they can contain white space.

Please help me. Thanks.

Answer 1

What's wrong with using string.split()?

string test = "-action=1";
string[] splitUp = test.Split("-=".ToCharArray());

I admit, though that this still gives you possibly more parameters than you'd like to see in the split up array...

[0] = ""
[1] = "action"
[2] = "1"

Answer 2

Don't use split, just use Match, and then get the results from the Groups collection by index (index 1 and 2).

Match match = regex.Match(myText);
if (!match.Success) {
    // the regex didn't match - you can do error handling here
}
string action = match.Groups[1].Value;
string number = match.Groups[2].Value;

Answer 3

Try this (updated to add Regex.Split):

string victim = "-action=1";
string[] stringSplit = victim.Split("-=".ToCharArray());
string[] regexSplit = Regex.Split(victim, "[-=]");

EDIT: Using your example:

string input = @"-destination=C:\Program Files\Release -action=value";
foreach(Match match in Regex.Matches(input, @"-(?<name>\w+)=(?<value>[^=-]*)"))
{
    Console.WriteLine("{0}", match.Value);
    Console.WriteLine("\tname  = {0}", match.Groups["name" ].Value);
    Console.WriteLine("\tvalue = {0}", match.Groups["value"].Value);
}
Console.ReadLine();

Of course, this code have issues if your path contains - character

Answer 4

In .NET Regex, you can name your groups.

string pattern = @"^-(?<MyKey>\S+)=(?<MyValue>\S+)$";
Regex regex = new Regex(pattern);
string myText = "-action=1";

Then do a "Match" and get the values by your group names.

Match theMatch = regex.Match(myText);
if (theMatch.Success)
{
    Console.Write(theMatch.Groups["MyKey"].Value); // This is "action"
    Console.Write(theMatch.Groups["MyValue"].Value); // This is "1"
}

Answer 5

In his talk Regular Expression Mastery, Mark Dominus attributes the following helpful rule to Learning Perl author (and fellow StackOverflow user) Randal Schwartz:

• Use capturing or m//g [or regex.Match(...)] when you know what you want to keep.
• Use split when you know what you want to throw away.