Addition of two numbers in Objective-C and displaying result - objective-c

Question

I have made a small app for iPhone, that can add two complex numbers(I have just started to learn).
In the program I can enter some number in the text field, program will process string and save numbers.
The problem for me is how to display addition of the two numbers.
What do I mean:
I have a function that can display real and imaginary part of true complex number instance, and it work fine:
- (void) functionDisplayInfo {
// number 1
if ([number1 functionProcessString:self.textEditComplexNumber1.text]) {
self.labelComplex1.text = [NSString stringWithFormat: #"true, %f, %f", number1.getRealValue, number1.getImgValue];
} else {
self.labelComplex1.text = #"false";
}
// number 2
if ([number2 functionProcessString:self.textEditComplexNumber2.text]) {
self.labelComplex2.text = [NSString stringWithFormat: #"true, %f, %f", number2.getRealValue, number2.getImgValue];
} else {
self.labelComplex2.text = #"false";
}
}
but when I try to do true addition of two real or imaginary parts of complex number it does not work. The code is similar to the code sample above. This is the code sample:
- (IBAction)functionAddition:(id)sender {
self.labelDisplayResult.text = [NSString stringWithFormat:#"result is: %f %f", number1.getRealValue + number2.getRealValue, number1.getImgValue + number2.getImgValue];
[self functionDisplayInfo];
}
This code displays only the 0.000.. and 0.000... when it should display result of addition.
Can somebody tell me what am I doing wrong. Thanks

Answer 1

Just a guess, as there is not enough information.
Reading your code it looks like the method functionProcessString: takes a string and parses a complex number from it. In functionDisplayInfo call this on number1 and number2 - so the method is misnamed, it parses and displays.
In your method functionAddition: you do the addition and then call functionDisplayInfo, this suggests you are doing the addition before the numbers have been parsed.
I suspect that whatever type number1 and number2 are it is initialised to zero and only changes after functionProcessString: is called, so doing the addition first gives you zero.
You might solve your problem by simply swapping the order of the two statements in functionAddition: so the parsing occurs first.
You might want to consider redesigning your code so that the parsing and display of your inputs is handled by separate methods. You can also do the same for output, separating the operation on the inputs from the display of its results. This might give you a cleaner design and avoid problems like you hit. E.g. under such a design your functionAddition: in pseudo-code would be:
- (IBAction)functionAddition:(id)sender
{
if ([self functionParseInput])
{
[self displayInput];
[self addInputs];
[self displayOutput];
}
}
HTH