I found following pattern from RegexLibrary, and i don't know how use Match to get Re and Im values. I'm new in Regex
. Is it a correct way to get data from a pattern?
If it's true, I need some sample code!
This is what i think it should be:
public static complex Parse(string s)
{
string pattern = @"([-+]?(\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-2]?\d{1,2})?[r]?|[-+]?((\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-2]?\d{1,2})?)?[i]|[-+]?(\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-2]?\d{1,2})?[r]?[-+]((\d+\.?\d*|\d*\.?\d+)([Ee][-+]?[0-2]?\d{1,2})?)?[i])";
Match res = Regex.Match(s, pattern, RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace);
// What should i do here? The complex number constructor is complex(double Re, double Im);
// on error...
return complex.Zero;
}
Thanks in advance!
I think they're overcomplicating the regex a bit, they are for example including support for scientific numbers and it seems that there are some errors in it.
Try this simpler regex instead.
class Program
{
static void Main(string[] args)
{
// The pattern has been broken down for educational purposes
string regexPattern =
// Match any float, negative or positive, group it
@"([-+]?\d+\.?\d*|[-+]?\d*\.?\d+)" +
// ... possibly following that with whitespace
@"\s*" +
// ... followed by a plus
@"\+" +
// and possibly more whitespace:
@"\s*" +
// Match any other float, and save it
@"([-+]?\d+\.?\d*|[-+]?\d*\.?\d+)" +
// ... followed by 'i'
@"i";
Regex regex = new Regex(regexPattern);
Console.WriteLine("Regex used: " + regex);
while (true)
{
Console.WriteLine("Write a number: ");
string imgNumber = Console.ReadLine();
Match match = regex.Match(imgNumber);
double real = double.Parse(match.Groups[1].Value, CultureInfo.InvariantCulture);
double img = double.Parse(match.Groups[2].Value, CultureInfo.InvariantCulture);
Console.WriteLine("RealPart={0};Imaginary part={1}", real, img);
}
}
}
Remember to try to understand every regex you use, never use them blindly. They need to be understood like any other language.