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Thread: Problem with detecting Math operation.

  1. #1
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    Question Problem with detecting Math operation.

    Hello,

    I am having trouble testing to see what Mathematica operator the user has in-putted.

    Here is the function (There are others so don't worry that this wouldn't actually run)

    public static void calc()
    	{
    		Scanner calcinputS = new Scanner(System.in);
    		String calcinput, op;
    		int answer, fnum, snum;
     
    		System.out.println("-------------------------");
    		System.out.println("|     Calculator v1.0   |");
    		System.out.println("-------------------------");
    		System.out.print("  Enter an equation: ");
    		calcinput = calcinputS.nextLine();
     
    		String[] calcinputA = calcinput.split(" ");
    		fnum = Integer.parseInt(calcinputA[0]);
    		op = calcinputA[1];
    		snum = Integer.parseInt(calcinputA[2]);
     
    		if (op == "+")
    		{
    			answer = fnum + snum;
    			System.out.println(answer);
    		}
    		else if (op == "-")
    		{
    			answer = fnum - snum;
    			System.out.println(answer);
    		}
    		else if (op == "*")
    		{
    			answer = fnum * snum;
    			System.out.println(answer);
    		}
    		else if (op == "/")
    		{
    			answer = fnum / snum;
    			System.out.println(answer);
    		}
    		else
    		{
    			System.out.println("Error: Could not recognize operation: " + op);
    		}
     
    	}

    Thank you


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Problem with detecting Math operation.

    You should use the equals() method for comparing Strings, not the == operator.
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: Problem with detecting Math operation.

    Ah, Thank you.

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