/**
 * Informatik II - FS2009 <br>
 * Uebungsserie 4, Aufgabe 2 <br>
 *
 * ...ADD YOUR COMMENTS HERE...
 */
public class Expr {

    char[] input;

    public Expr(char[] c) {
        input = c;
    }

    /**
     * "...ADD YOUR COMMENTS HERE..."
     */
    public int evalExpr() {
        //evaluate expression starting from index 0
        return this.evalExprRec( 0 );
    }

    /**
     * "...ADD YOUR COMMENTS HERE..."
     */
    public int evalExprRec(int i) {

        if (!Character.isDigit( input[i] )) {
            System.out.println("Error .... ");
            System.exit( 1 );
        }

        // stop condition?
        // syntax check?
        // recursive call?
        // return value?

        return -1; // this return instruction is here only as a placeholder!!
    }


    public static void main( String[] args ) {
        if( args.length != 1) {
            System.out.println("Please enter a correct input!");
            System.out.println("Example: java Expr \"1*2*3*4\"" );
            System.exit( 1 );
        }

        Expr expression = new Expr(args[0].toCharArray());
        int result = expression.evalExpr();

        System.out.println( "The evaluation of "
                + args[0] +
                " gives: " + result  );
    }
}