Question

I am developing in Cocoa / Xcode and have an int * array containing values.
When I want to use memcpy to shift values in the array, it transfers only 0s.

e.g.

• Array contains values as 1 2 3 4
• memcpy(array,array+2*sizeof(int),2*sizeof(int));

result: 0,0,3,4

Is there a better alternative to memcpy, or something I am doing wrong ?

Answer 1

I think the right way to do what you want is:

memcpy(array, array + 2, 2*sizeof(int));

That’s because in the 2nd argument of memcpy pointer arithmetic is being done, and anything that’s being added to “array” pointer is considered as being a multiple of an integer’s size. So in this case saying “array + 2” means “the integer pointer `array’ plus two times the size of an integer”.