如何使用带有指针的指针的记忆？

Question

I have the following struct in C:

typedef struct {
double value;
char* name;
} COMPONENT;

And I have the following vector of pointers:

COMPONENT **list = malloc(sizeof(COMPONENT*)*100);

This list contains only 10 pointers of COMPONENT struct even allocated for 100 elements, ok. Now, I want to insert at the first position a new COMPONENT using the memmove:

memmove(list+sizeof(COMPONENT*), list, sizeof(COMPONENT*)*10);
list[0] = new_element_ptr;

But this operation is not working =[. I'm losing all other references (list[1], list[2] and so on...). Is this differents because it is a struct and my vector have only pointers?

Answer 1

This is what you are looking for:

memmove(list + 1, list, sizeof(list[0]) * 10);

When adding to pointers, you are not adding byte offsets, you are adding number of elements.