Optimal way to perform a shift operation on an array

Question

Suppose I have an array

unsigned char arr[]= {0,1,2,3,4,5,6,7,8,9};

Is there a way to perform shift operation on them besides just copying them

Answer 1

As long as the array is modifiable, you can use memmove to shift them (but don't mistakenly use memcpy as memcpy is not meant for overlapping regions):

memmove(&arr[0], &arr[1], sizeof(arr) - sizeof(*arr));

(sizeof(arr) - sizeof(*arr) is the size in bytes of all but 1 element of the array).