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  1. #1
    marksey07 is offline Member
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    Default Simple question...I hope

    Java Code:
    public class Calculator2 {
    	public static void main(String[] args){
    		double result = result_of("17+28-11");
    		System.out.println(result);
    	}
    
    	public static double result_of(String equation)
    	{
    		if(equation.contains("+"))
    		{
    			//equation.split not String.split
    			String[] split_up_equation = equation.split("[+]");
    			double result = 0.0;
    			for(int i=0;i<split_up_equation.length;i++)
    			{
    				//add the double value
    				result += result_of(split_up_equation[i]);
    			}
    			return result;
    		}
    		if(equation.contains("-"))
    		{
    			String[] split_up_equation = equation.split("[-]");
    			double result = 0.0;
    			for(int i=0;i<split_up_equation.length;i++)
    			{
    				result += result_of(split_up_equation[i]);
    			}
    			return result;
    		}
    		return Double.valueOf(equation);
    	}
    }
    This is my code for a calculator, as you can see the method for"-" adds rather than takes away. I don't believe there is a -= rather than +=

    Can anyone help me

  2. #2
    JosAH's Avatar
    JosAH is offline Moderator
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    Default

    Quote Originally Posted by marksey07 View Post
    This is my code for a calculator, as you can see the method for"-" adds rather than takes away. I don't believe there is a -= rather than +=
    Yup, there's a -= operator for numbers: a-= b subtracts the value b from the value a and assigns it to a again, no problem.

    kind regards,

    Jos
    I have the stamina of a seal; I lie on the beach instead of running on it.

  3. #3
    KevinWorkman's Avatar
    KevinWorkman is offline Crazy Cat Lady
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    Quote Originally Posted by marksey07 View Post
    I don't believe there is a -= rather than +=
    What happened when you tried? Keep in mind that you don't have to use the += operator; it's just a shortcut for doing something like this:

    Java Code:
    int x = 7;
    x = x + 2; // same as x += 2;
    PS- In the future, you might want to use a more meaningful post title. People tend to ignore posts with generic titles like this one.

    Edit- Too slow! But recommended reading: http://download.oracle.com/javase/tu...bolts/op1.html
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  4. #4
    marksey07 is offline Member
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    Default

    so
    Java Code:
    if(equation.contains("-"))
    		{
    			String[] split_up_equation = equation.split("[-]");
    			double result = 0.0;
    			for(int i=0;i<split_up_equation.length;i++)
    			{
    				result -= result_of(split_up_equation[i]);
    			}
    			return result;
    		}
    		return Double.valueOf(equation);
    and
    Java Code:
    double result = result_of("50-20");
    should return 30?

  5. #5
    JosAH's Avatar
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    Quote Originally Posted by marksey07 View Post
    Java Code:
    double result = result_of("50-20");
    should return 30?
    I don't know what your result_of( ... ) method does but if it is even half sane I'd expect that result yes. What's keeping you from trying the code, don't take my word for it.

    kind regards,

    Jos
    I have the stamina of a seal; I lie on the beach instead of running on it.

  6. #6
    KevinWorkman's Avatar
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    Quote Originally Posted by marksey07 View Post
    so
    Java Code:
    if(equation.contains("-"))
    		{
    			String[] split_up_equation = equation.split("[-]");
    			double result = 0.0;
    			for(int i=0;i<split_up_equation.length;i++)
    			{
    				result -= result_of(split_up_equation[i]);
    			}
    			return result;
    		}
    		return Double.valueOf(equation);
    and
    Java Code:
    double result = result_of("50-20");
    should return 30?
    Again- what happened when you tried it?
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  7. #7
    marksey07 is offline Member
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    Default

    OK, didn't work. But im just going to have a play, I have a good feeling I'm going to get there :) :eek:

    Thanks guys

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