Array of floating point values in Objective-C - objective-c

Question

How can I create array of floating point numbers in Objective-C?
Is it possible?

Answer 1

You can create a dynamic array (size decided at runtime, not compile time) in different ways, depending on the language you wish to use:
Objective-C
NSArray *array = [[NSArray alloc] initWithObjects:
[NSNumber numberWithFloat:1.0f],
[NSNumber numberWithFloat:2.0f],
[NSNumber numberWithFloat:3.0f],
nil];
...
[array release]; // If you aren't using ARC
or, if you want to change it after creating it, use an NSMutableArray:
NSMutableArray *array = [[NSMutableArray alloc] initWithCapacity:0];
[array addObject:[NSNumber numberWithFloat:1.0f]];
[array addObject:[NSNumber numberWithFloat:2.0f]];
[array addObject:[NSNumber numberWithFloat:3.0f]];
...
[array replaceObjectAtIndex:1 withObject:[NSNumber numberWithFloat:99.9f]];
...
[array release]; // If you aren't using ARC
Or using the new-ish Objective-C literals syntax:
NSArray *array = #[ #1.0f, #2.0f, #3.0f ];
...
[array release]; // If you aren't using ARC
C
float *array = (float *)malloc(sizeof(float) * 3);
array[0] = 1.0f;
array[1] = 2.0f;
array[2] = 3.0f;
...
free(array);
C++ / Objective-C++
std::vector<float> array;
array[0] = 1.0f;
array[1] = 2.0f;
array[2] = 3.0f;

Answer 2

For an dynamic approach you can use NSNumber object and add it to NSMutableArray, or if you need only static array then use suggestions from comments, or use standard C.
like:
NSMutableArray *yourArray = [NSMutableArray array];
float yourFloat = 5.55;
NSNumber *yourFloatNumber = [NSNumer numberWithFloat:yourFloat];
[yourArray addObject:yourFloatNumber];
and then to retrive:
NSNumber *yourFloatNumber = [yourArray objectAtIndex:0]
float yourFloat = [yourFloatNumber floatValue];

Answer 3

If you are using Xcode 4.4+, you can try this:
NSArray *a = #[ #1.1f, #2.2f, #3.3f];
Here is all new literals of LLVM Compiler 4.0.

Answer 4

How about something like this?
#interface DoubleArray : NSObject
#property(readonly, nonatomic) NSUInteger count;
#property(readonly, nonatomic) double *buffer;
- (instancetype)init NS_UNAVAILABLE;
- (instancetype)initWithCount:(NSUInteger)count NS_DESIGNATED_INITIALIZER;
- (double)valueAtIndex:(NSUInteger)idx;
- (void)setValue:(double)value atIndex:(NSUInteger)idx;
#end
#implementation DoubleArray
- (void)dealloc
{
if (_buffer != 0) {
free(_buffer);
}
}
- (instancetype)initWithCount:(NSUInteger)count
{
self = [super init];
if (self) {
_count = count;
_buffer = calloc(rows * columns, sizeof(double));
}
return self;
}
- (double)valueAtIndex:(NSUInteger)idx
{
return *(_buffer + idx);
}
- (void)setValue:(double)value atIndex:(NSUInteger)idx
{
*(_buffer + idx) = value;
}
#end
It's a basic array. You can extend this with more complex features like appending, indexed removal etc.