I have a string that looks like this:
var expression = @"Args("token1") + Args("token2")";
I want to retrieve a collection of strings that are enclosed in Args("") in the expression.
How would I do this in C# or VB.NET?
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4 Answers
Regex:
string expression = "Args(\"token1\") + Args(\"token2\")";
Regex r = new Regex("Args\\(\"([^\"]+)\"\\)");
List<string> tokens = new List<string>();
foreach (var match in r.Matches(expression)) {
string s = match.ToString();
int start = s.IndexOf('\"');
int end = s.LastIndexOf('\"');
tokens.add(s.Substring(start + 1, end - start - 1));
}
Non-regex (this assumes that the string in the correct format!):
string expression = "Args(\"token1\") + Args(\"token2\")";
List<string> tokens = new List<string>();
int index;
while (!String.IsNullOrEmpty(expression) && (index = expression.IndexOf("Args(\"")) >= 0) {
int start = expression.IndexOf('\"', index);
string s = expression.Substring(start + 1);
int end = s.IndexOf("\")");
tokens.Add(s.Substring(0, end));
expression = s.Substring(end + 2);
}
Comments
There is another regular expression method for accomplishing this, using lookahead and lookbehind assertions:
Regex regex = new Regex("(?<=Args\\(\").*?(?=\"\\))");
string input = "Args(\"token1\") + Args(\"token2\")";
MatchCollection matches = regex.Matches(input);
foreach (var match in matches)
{
Console.WriteLine(match.ToString());
}
This strips away the Args sections of the string, giving just the tokens.
Comments
If you want token1 and token2, you can use following regex
input=@"Args(""token1"") + Args(""token2"")"
MatchCollection matches = Regex.Matches(input,@"Args\(""([^""]+)""\)");
Sorry, If this is not what you are looking for.
3 Comments
cless
Forgot to add, is there a non regex solution to my question? Thanks!
YOU
Imm.., parsing char by char will be more difficult I think.
cless
Yeah i agree, I was worried at first at the performance of .Net's Regex, so i speculated that a non- Regex solution would be faster... It appears that it's fairly fine...
if your collection looks like this:
IList<String> expression = new List<String> { "token1", "token2" };
var collection = expression.Select(s => Args(s));
As long as Args returns the same type as the queried collection type this should work okay
you can then iterate over the collection like so
foreach (var s in collection)
{
Console.WriteLine(s);
}
