I want to do achieve something like this in Objective-C
+(int[10][10])returnArray
{
int array[10][10];
return array;
}
However, this gives an "array initializer must be an initializer list" compiler error. Is this at all possible?
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2 Answers
You can't return an array (of any dimension) in C or in Objective-C. Since arrays aren't lvalues, you wouldn't be able to assign the return value to a variable, so there's no meaningful for such a thing to happen. You can work around it, however. You'll need to return a pointer, or pull a trick like putting your array in a structure:
// return a pointer
+(int (*)[10][10])returnArray
{
int (*array)[10][10] = malloc(10 * 10 * sizeof(int));
return array;
}
// return a structure
struct array {
int array[10][10];
};
+(struct array)returnArray
{
struct array array;
return array;
}
3 Comments
Carl Norum
Looking at that code, it appears I use
array in lot of different namespaces. I'll clean it up if you think it's confusing.
Rory Harvey
When using the struct method, how do I access the struct as a 2d array? For instance when I do
int i = array[0][1] I get "subscripted value is not an array, pointer, or vector"Carl Norum
You need to access the structure member.
int i = array.array[0][1] should do it for you.Another way you can do it with objective C++, is to declare the array as follows:
@interface Hills : NSObject
{
@public
CGPoint hillVertices[kMaxHillVertices];
}
This means the array is owned by the Hills class instance - ie it will go away when that class does. You can then access from another class as follows:
_hills->hillVertices
I prefer the techniques Carl Norum describes, but wanted to present this as an option that might be useful in some cases - for example to pass data into OpenGL from a builder class.
