textcalculator v2.0 alpha

program textcalculator;

uses
  SysUtils; // Required for string operations and conversions.

var
  input: string;
  num1, num2, result: Real;
  op: Char;

begin
  WriteLn('Welcome to the Text-Based Calculator!');
  WriteLn('Enter an expression (e.g., 2 + 5, 10 / 2):');
  WriteLn('Operators supported: + (add), - (subtract), * (multiply), / (divide)');
  WriteLn('Type "exit" to quit.');

  repeat
    Write('> ');
    ReadLn(input);

    // Exit the program if user types "exit"
    if LowerCase(input) = 'exit' then
      Break;

    try
      // Find the operator in the input string
      if Pos('+', input) > 0 then
        op := '+'
      else if Pos('-', input) > 0 then
        op := '-'
      else if Pos('*', input) > 0 then
        op := '*'
      else if Pos('/', input) > 0 then
        op := '/'
      else
        raise Exception.Create('Invalid operator! Use +, -, *, or /.');

      // Split the input into two numbers based on the operator
      case op of
        '+': begin
          num1 := StrToFloat(Trim(Copy(input, 1, Pos('+', input) - 1)));
          num2 := StrToFloat(Trim(Copy(input, Pos('+', input) + 1, Length(input))));
          result := num1 + num2;
        end;
        '-': begin
          num1 := StrToFloat(Trim(Copy(input, 1, Pos('-', input) - 1)));
          num2 := StrToFloat(Trim(Copy(input, Pos('-', input) + 1, Length(input))));
          result := num1 - num2;
        end;
        '*': begin
          num1 := StrToFloat(Trim(Copy(input, 1, Pos('*', input) - 1)));
          num2 := StrToFloat(Trim(Copy(input, Pos('*', input) + 1, Length(input))));
          result := num1 * num2;
        end;
        '/': begin
          num1 := StrToFloat(Trim(Copy(input, 1, Pos('/', input) - 1)));
          num2 := StrToFloat(Trim(Copy(input, Pos('/', input) + 1, Length(input))));
          if num2 = 0 then
            raise Exception.Create('Error: Division by zero is not allowed!');
          result := num1 / num2;
        end;
      end;

      // Output the result
      WriteLn('Result: ', result:0:2);
    except
      on E: Exception do
        WriteLn('Error: ', E.Message);
    end;

  until False;

  WriteLn('Thank you for using the calculator!');
end.