I am trying to make a 2D byte array.
Can anybody give the code how to declare a NULL 2D byte array in Objective-C?
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2 Answers
Since objective-c is a strict superset of c, you could just use a pure c definition and it would work fine:
char** myMatrix = malloc(width*height);
You could also use an NSArray of NSArrays, but that's not a 2 dimensional array. It's a jagged array and considerably less easy to use than a plain byte array.
Another alternative is using an NSData/NSMutableData object. That is the Foundation way of working with byte arrays. See NSMutableData class reference for more information.
NSMutableData* data = [NSMutableData dataWithLength:1024]; // One kilobyte
void* dataPointer = [data mutableBytes]; // Get a pointer to the raw bytes
3 Comments
Matthew Scharley
Probably want to make that a char** myMatrix, so you can use the more normal notation of myMatrix[x][y]
Gerco Dries
No, because byte is not a C type. The definition does not exist in the C language. Please also see the comment I added about NSData.
Gerco Dries
What do you mean by a null data? I assume you don't mean a null pointer of type char** (or void*) because that would be kind of silly. Perhaps we need a little more context in order to answer your question.
I'm cheating by doing this in C.
size_t width;
size_t height;
unsigned char *twoDimArray = calloc(width*height);
1 Comment
kbyrd
Neither the C or C++ standard has a 'byte' type. I don't know about Objective C.