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Simple if statement for checking whether a co-ordinate is inside a square?

Answer 1

+5 A:

I think a better solution would be to use CGRectContainsPoint:

CGRect rect = CGRectMake(46, 18, 124 - 46, 75 - 18);
if (CGRectContainsPoint(rect, touchedAt))
   // do whatever

Todd Yandell 2010-03-20 19:59:19

This is a good alternative. As noted, your "shorter" syntax in the question is incorrect.

calmh 2010-03-20 20:02:25

I guess this is where coming from a PHP background doesn't help sometimes. I like this alternative very much, it's a much nicer solution than what I am currently doing. However, I also like that Steve told me *why* my shorter version doesn't work.

JonB 2010-03-20 20:04:49

As a general rule in Apple's APIs, any datatype defined by a framework usually has comparison functions written for it. This is especially true if the comparisons are very common such as this one. Moral: Look for the functions before writing code to duplicate them.

TechZen 2010-03-20 20:32:39

Answer 2

+2 A:

Some languages support the "simple" version (Python, for example) but the C family doesn't.

In C family languages, the comparison operators are binary operators that return a boolean. One operator, two parameters, one result. Try to add another comparison and you end up comparing your boolean result against the next value. That's why you need all the && operators.

I don't know Objective-C, but I assume it does what C does.

To simplify, just write a simple function (perhaps inline) called "bounds_check" or "range_check" or similar that takes three parameters. Or better still, use one that's already written.

Steve314 2010-03-20 19:59:29

Objective-C is a strict superset of C. It does everything C does, exactly how C does it.

chpwn 2010-03-20 20:22:05

@chpwn - very interesting. I keep meaning to take a look, but you know how it is - so many languages etc. Still, I'm interested in LLVM, so I'll certainly get around to playing with clang at some time, and that has objective C support IIRC.

Steve314 2010-03-20 20:27:34

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Simple if statement for checking whether a co-ordinate is inside a square?

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