public static string SimpSub(string s)
{
// If there is subtraction.
if (s.IndexOf('-') != -1)
{
// Index of the multiplication sign.
int multIndex = s.IndexOf('-');
// The minuend.
string X = "";
// The subtrahend.
string Y = "";
// Index that finds the minuend.
int startIndex = multIndex - 1;
// Getting the minuend.
while (startIndex > -1 && (Char.IsDigit(s[startIndex]) ||
s[startIndex] == '/' || (startIndex == 0 && s[startIndex] == '-')))
{
X = s[startIndex] + X;
startIndex--;
}
// Index that finds the subtrahend.
int endIndex = multIndex + 1;
// Getting the subtrahend.
while (endIndex < s.Length && (Char.IsDigit(s[endIndex]) ||
s[endIndex] == '/' || (endIndex == multIndex + 1 && s[endIndex] == '-')))
{
Y += s[endIndex];
endIndex++;
}
// Creating buffers for future fractions.
Fraction xFrac = new Fraction();
Fraction yFrac = new Fraction();
if (X != "" && Y != "")
{
// If both can be fractions then calcualte and add to the original string.
if (CreateFraction(X, ref xFrac) && CreateFraction(Y, ref yFrac))
{
string result = Calculations.Minus(xFrac, yFrac).ToString();
s = s.Substring(0, startIndex + 1) + result + s.Substring(endIndex, s.Length - endIndex);
}
else
{
MessageBox.Show("Input error!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
s = "Cannot be calculated!";
return(s);
}
}
else
{
if (X == "")
{
if (CreateFraction(Y, ref yFrac))
{
s = "-" + yFrac.ToString();
}
else
{
MessageBox.Show("Input error!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
s = "Cannot be calculated!";
return(s);
}
}
else
{
s = X;
}
}
}
return(s);
}
// Function to create a fraction object.
public static bool CreateFraction(string s, ref Fraction fraction)
{
// If there are / symbols.
if (s.IndexOf('/') != -1)
{
// Getting the array of symbols.
string[] frac = s.Split('/');
int buf;
// Future numerator.
int numer = 0;
// Future denominator.
int denom = 1;
// Checking all the symbols.
for (int i = 0; i < frac.Length; i++)
{
// If it's an integer then add it.
if (Int32.TryParse(frac[i], out buf))
{
// The 1st integer is the numerator.
if (i == 0)
{
numer = Convert.ToInt32(frac[i]);
}
// The multiplication of the rest is the denominator.
else
{
denom *= Convert.ToInt32(frac[i]);
}
}
// If it's not an integer then can't create a fracton.
else
{
return(false);
}
}
try
{
fraction = new Fraction(numer, denom);
}
catch
{
return(false);
}
return(true);
}
else
{
try
{
fraction = new Fraction(Convert.ToInt32(s), 1);
}
catch
{
return(false);
}
return(true);
}
}
public static double ToDecimal(Fraction curFrac)
{
return((double)(curFrac.Numerator) / curFrac.Denominator);
}
public static Fraction Divide(Fraction a, Fraction b)
{
return(a / b);
}
public static Fraction Multiply(Fraction a, Fraction b)
{
return(a * b);
}
public static Fraction Minus(Fraction a, Fraction b)
{
return(a - b);
}
public static Fraction Plus(Fraction a, Fraction b)
{
return(a + b);
}