You have 3 items in array, in this case, index can be 0, 1 or 2.
You can do the following test :
for(i=0;i<=2;i++)
or
for(i=0;i<3;i++)
or
for(i=0;i<sizeof(abc)/sizeof(abc[0]);i++)
the last one can only be used because the array size of abc is set at the definition of the variable (implicitely in this case, explicite will be "int abc[3];").
It cannot be used with those:
int NbItems(int abc[]) { return sizeof(abc)/sizeof(abc[0]);}
int* abc; abc = new int[3];