CODEWITHSUNDEEP
javacalculatormultiplication
Anton Shvets
Anton Shvets

Reputation: 41

Multiplication doesnt work in simple java calculator

I'm trying to create a basic calculator. Here is my code:

public class Calc2 {
public static void main(String[] args) {
    String[] calcArray;
    calcArray = new String[3];
    calcArray[0] = args[0];
    calcArray[1] = args[1];
    calcArray[2] = args[2];
    double result = 0;

    if (args.length == 3) {
    double firstNumber = Double.parseDouble(args[0]);   
    int operator = args[1].charAt(0);           
    double secondNumber = Double.parseDouble(args[2]);      
    System.out.print(args[0] + " " + args[1] + " " + args[2] + " = ");

    switch (operator)
    {
        case ('+'):
            result = firstNumber + secondNumber; 
            break;
        case ('-'):
            result = firstNumber - secondNumber; 
            break;
        case ('*'):
            result = firstNumber * secondNumber; 
            break;
        case ('/'):
            result = firstNumber / secondNumber; 
            break;
        default:
            System.out.println("Invalid Operator selected");
    }
        System.out.printf(" " + result);    
            }           
    else
    {       
        System.out.println("Incorrect arguments quantity");
    }       
}
}

Seems that "-","+","/" operators works correctly, but when i try to execute multiplication in this code, for example:

java Calc2 4 * 3

Program displays following result:

Incorrect argument quantity

Please explain, why it happens and how to fix it. Thanks.

Upvotes: 3

Views: 691

Answers (2)

Zbynek Vyskovsky - kvr000
Zbynek Vyskovsky - kvr000

Reputation: 18825

* is expanded by the shell, therefore you'll get list of files as arguments. You need to escape:

java Calc2 4 "*" 3

Upvotes: 2

rgettman
rgettman

Reputation: 178263

The * character typed on the command line is interpreted by the shell as a globbing character, meaning all files in the current directory. The command line being fed to Java is something like

3 Calc2.class Calc2.java 4

plus any other files that may be present.

Escape it in the shell (or single-quote it to avoid shell interpretation).

java Calc2 3\* 4

or

java Calc2 3 '*' 4

Upvotes: 7

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