// Reads the statement preceding the index location of the NON-UNARY operator
// SyntaxException is thrown if the character to the IMMEDIATE left is an operator
private string ReadLeft(string statement, int operatorIndex)
{
if (StatementChecker.IsOperator(statement[operatorIndex - 1]))
{
throw new SyntaxException();
}
int counter = 1;
for (int index = operatorIndex - 1; index > -1; index--)
{
// Checks for beginning of statement, OR the appearance of the next NON-UNARY operator
// Returns the number BEFORE the operator
if (index == 0)
{
return(statement.Substring(index, counter));
}
else if (StatementChecker.IsArithmeticOperator(statement[index], statement, index))
{
return(statement.Substring(index + 1, counter - 1));
}
counter++;
}
return(null);
}
static void Main(string[] args)
{
try
{
if (!StatementChecker.IsValidArgument(args))
{
Console.WriteLine(Constants.INVALID);
}
else
{
Calculator calculator = new Calculator(args[0]);
calculator.CalculateStatement();
calculator.PrintSolution();
}
}
catch (SyntaxException)
{
Console.WriteLine(Constants.INVALID);
}
catch (OverflowException)
{
Console.WriteLine(Constants.OVERFLOW);
}
catch (DivideByZeroException)
{
Console.WriteLine(Constants.ZERO_DIVISION);
}
}
// Reads the statement following index location of the operator
// Checks for the end of the statement, OR the appearance of the next NON-unary operator
// Returns the next number AFTER the operator
private string ReadRight(string statement, int operatorIndex)
{
int counter = 1;
for (int index = operatorIndex + 1; index < statement.Length; index++)
{
if (index == statement.Length - 1)
{
return(statement.Substring(operatorIndex + 1, counter));
}
else if (StatementChecker.IsArithmeticOperator(statement[index], statement, index))
{
return(statement.Substring(operatorIndex + 1, counter - 1));
}
counter++;
}
return(null);
}
// Calculate statement based on specified operations
// operations = operations to be processed
private string Calculate(string operations)
{
// process statement if specified operators exist
// if found, read the left and right numbers and calculate
// recurse until no specified operators are left and return answer
if (StatementChecker.OperatorCount(statement, operations) != 0)
{
for (int x = 0; x < statement.Length - 1; x++)
{
if (operations.Contains(statement[x]) &&
!StatementChecker.IsUnaryOperator(statement[x], statement, x))
{
statement = CalculateLeftandRight(statement, statement[x], x);
statement = Calculate(operations);
break;
}
}
}
return(statement);
}