ExpressionCalculator

System.out.println("CC"); System.out.println("Welcome to the Calculator program."); System.out.println("You can enter a SIMPLE mathematical expression and the program will print the value."); System.out.println("1 + 2 is a SIMPLE expression: it has a SINGLE operator with an operand on each side."); System.out.println("(Note the pa operator allows Calculator to be used as an accumulator by entering pa + 5"); System.out.println("or to calculate expressions with more than 2 operators, e.g. 5.7 x 5.7 followed by pi x pa"); System.out.println("Operators can be + - x or / and operands can be a number or pi or pa (for previous answer)."); System.out.println("The operands may also be preceded by a + or - sign, so -1 + -2 = -3, and -1 - -2 = 1"); System.out.println("Enter EXIT instead of an expression to terminate the program.");