c# split input of a string

Question

I've recently moved from c++ to c# in my classes and I have looked all over and haven't found much. I am having the following problem. I am supposed to be able to let the user add a complex number. For Example

-3.2 - 4.1i I want to split and store as (-3.2) - (4.1i)

I know I can split at the - sign, but there are some problems like

4 + 3.2i or even just a single number 3.2i.

Any help or insight would be appreciated.

Answer 1

By matching all the valid input with a regex it's a matter of assembling it after. The regex works by

• [0-9]+ matching 0-n numbers
• [.]? matching 0 or 1 dot
• [0-9]+ matching 0-n numbers
• i? matching 0 or 1 "i"
• | or
• [+-*/]? matching 0 or 1 of the operators +, -, * or /

.

public static void ParseComplex(string input)
{
    char[] operators = new[] { '+', '-', '*', '/' };

    Regex regex = new Regex("[0-9]+[.]?[0-9]+i?|[+-/*]?");
    foreach (Match match in regex.Matches(input))
    {
        if (string.IsNullOrEmpty(match.Value))
            continue;

        if (operators.Contains(match.Value[0]))
        {
            Console.WriteLine("operator {0}", match.Value[0]);
            continue;
        }

        if (match.Value.EndsWith("i"))
        {
            Console.WriteLine("imaginary part {0}", match.Value);
            continue;

        }
        else
        {
            Console.WriteLine("real part {0}", match.Value);

        }
    }
}