Simple question...I hope

[marksey07]

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

[JosAH]

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

[KevinWorkman]

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:

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

[marksey07]

so

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

double result = result_of("50-20");

should return 30?

[JosAH]

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

[KevinWorkman]

so

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

double result = result_of("50-20");

should return 30?

Again- what happened when you tried it?

[marksey07]

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