Strange math in Objective C
I am getting an unexpected value with a simple math calculation in Objective C. I have outputted three different parts of the calculation, as well as the result of the calculation below.
The following code
NSLog(@"self.contentView.bounds.size.width: %f", self.contentView.bounds.size.width);
NSLog(@"SWATCHES_WIDTH: %f", SWATCHES_WIDTH);
NSLog(@"RIGHT_MARGIN: %f", RIGHT_MARGIN);
NSLog(@"(self.contentView.bounds.size.width - SWATCHES_WIDTH - RIGHT_MARGIN): %f", (self.contentView.bounds.size.width - SWATCHES_WIDTH - RIGHT_MARGIN));
gives the following output:
self.contentView.bounds.size.width: 288.000000
SWATCHES_WIDTH: 82.000000
RIGHT_MARGIN: 12.000000
(self.contentView.bounds.size.width - SWATCHES_WIDTH - RIGHT_MARGIN): 214.000000
I expect the result to be 194 instead of 214 (288-82-12 = 194). Can anyone please give some insight into why this is calculated the way it is and what can I do to fix it? Thank!
As far as I know, all three of these values are CGFloats. The two constants are defined as follows:
#define SWATCHES_WIDTH SWATCH_SIZE * 3.0 + SPACE_BETWEEN * 2.0
#define RIGHT_MARGIN 12.0
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It:
self.contentView.bounds.size.width - SWATCHES_WIDTH - RIGHT_MARGIN
applies to this:
self.contentView.bounds.size.width - SWATCH_SIZE * 3.0 + SPACE_BETWEEN * 2.0 - RIGHT_MARGIN
What do you really want:
self.contentView.bounds.size.width - SWATCH_SIZE * 3.0 - SPACE_BETWEEN * 2.0 - RIGHT_MARGIN
self.contentView.bounds.size.width - (SWATCH_SIZE * 3.0 + SPACE_BETWEEN * 2.0) - RIGHT_MARGIN
You need to add parentheses around it for it to expand correctly:
#define SWATCHES_WIDTH (SWATCH_SIZE * 3.0 + SPACE_BETWEEN * 2.0)
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Block CPP Again!
Your subtraction after running cpp comes from this:
(self.contentView.bounds.size.width - SWATCHES_WIDTH - RIGHT_MARGIN)
:
(self.contentView.bounds.size.width - SWATCH_SIZE * 3.0 + SPACE_BETWEEN * 2.0 - 12.0)
See the problem?
You want SWATCHES_WIDTH to expand with parsers around it so you get what you expect
(self.contentView.bounds.size.width - (SWATCH_SIZE * 3.0 + SPACE_BETWEEN * 2.0) - 12.0)
So, you are subtracting, not adding SPACE_BETWEEN*2.0
to your result.
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