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.
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 numbersi? 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);
}
}
}
This still has pleanty of flaws and ways it can blow up, but in kinda works.
struct Complex
{
float re, im;
public static Complex Parse(string text)
{
text=text.Replace(" ", string.Empty); //trim spaces
float re=0, im=0;
int i_index=text.IndexOf('i');
if(i_index>=0) //if no 'i' is present process as real only
{
text=text.Substring(0, i_index); //ignore all after i
int i=0;
//find start of digits
while(i<text.Length&&(text[i]=='+'||text[i]=='-'))
{
i++;
}
//find end of digits
while(i<text.Length&&(char.IsNumber(text, i)|| text.Substring(i).StartsWith(CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator)))
{
i++;
}
// parse real (first) portion
float.TryParse(text.Substring(0, i), out re);
// had 'i' but no numbers
if(text.Length==0)
{
im=1;
}
else
{
//parse remaining value as imaginary
text=text.Substring(i+1);
float.TryParse(text, out im);
}
}
else
{
float.TryParse(text, out re);
}
// Build complex number
return new Complex() { re=re, im=im };
}
public override string ToString()
{
return string.Format("({0},{1})", re, im);
}
}
class Program
{
static void Main(string[] args)
{
var test=new[] { "1", "i", "5+2i", "-5+2i", "+5-2i", "0.23+0.72i" };
for(int i=0; i<test.Length; i++)
{
Debug.Print( Complex.Parse(test[i]).ToString() );
}
}
}
resut:
(1,0)
(0,1)
(5,2)
(-5,2)
(5,2)
(0.23,0.72)
i: likely4is perfectly valid complex number for that assignment (need teacher's input here :) )System.Numerics.Complexdoes not haveParseof any kind - so useful to store, no use for parsing.