Background: I'm working on an indicator in R that's so extremely slow I have to implement a cache. My indicator gives back a struct (inner). My cache uses a struct (outer) containing the price boundaries, for which the indicator would return the exact same value (fortunately this is the case!).

I want to use nested structs in order to not have to copy the inner struct one element at a time. I also don't want to have to adapt the outer struct if I make changes to the inner struct.


I think I must use memcpy. The manual tells us:

Quote
memcpy(void* dest, void* src, long size)
Copies size bytes from src to dest. Can be used to copy a whole struct or array with a single function.

Link


This is some demo code:

Code
function main()
{
	typedef struct
	{
		int inside_element;
	} INNER;
	typedef struct
	{
		int outside_element;
		INNER nested;
	} OUTER;
	INNER inner;
	OUTER outer;
	inner.inside_element = 42; //prepare the element to get nested
	outer.outside_element = 13; //some element in the outer struct
	outer.nested = inner; //try to store the inner struct into the outer struct
	//Error in 'line 21: 
	//Syntax error: Wrong type EQU:STRUCT@16::STRUCT@16
	//memcpy(outer.nested, inner, sizeof(inner)); //tried something. Not working when declaring inner and outer as pointers either
	INNER test = outer.nested; //read back the nested struct
	printf("\nnested element: %d; other element: %d", test.inside_element, outer.outside_element);
}


I'm curious about the solution! I hope somebody can help.