Assume again that the array address (i.e., address of a[0]) is

 -72(%ebp)
   

and the variable i is stored in memory at:

 -4(%ebp)
   

What assembler code would do this:

 a[i] = 100;
   

Answer: First the address of a[i] would be

  -72(%ebp) + 4 * i
   

But the compiler could have generate code that does the multiplication during execution since the value of i is not a constant.

 movl -4(%ebp), %eax
 movl $100, -72(%ebp, %eax, 4)