The sizeof() operator gives you the number of bytes required for storing an object. It also operates on a data type or a value.

Another way of determining the size of an object is to use pointer arithmetic, as in the following example:

struct point {    long x, y;};int main(){    struct point pt = {0}, *ppt = &pt;    unsigned char *p1 = NULL, *p2 = NULL;    size_t size = 0;    p1 = (unsigned char*)(ppt);    p2 = (unsigned char*)(++ppt);    size = p2 - p1; // size is now 8 bytes (2 longs)    // same as sizeof(struct point) or sizeof(pt)    return 0;}