sum (adding 2 numbers ) without plus operator

Question

Can anyone explain the logic how to add a and b?

#include 

int main()
{
     int a=30000, b=20, sum;
     char *p;
             


        

Answer 1

char *p;  

p is a pointer (to element with size 1 byte)

---

p=(char *)a;  

now p points to memory with address a

---

sum= (int)&p[b]; 

p pointer can be use as array p[] (start address (in memory) of this array is a)

p[b] means to get b-th element - this element address is a+b

[ (start address)a + b (b-th element * size of element (1 byte)) ]

&p[b] means to get address of element at p[b] but its address is a+b

---

if you use pointer to int (mostly 4 bytes)

int* p
p = (int*)a;

your sum will be a+(4*b)