Modify bit of a no. “n” at position “p” by “value”(0,1);

n=(n& ~(1UL<<p))|(value<<p);

Example:

let n=15(1111)

here bit position p is supposed from right to left (3,2,1,0)

p=2

Step 1: x=1UL<<p=100;(clearing the bit at position p)

Step 2: ~x=011(1’s compliment)

Step 3: n&(1UL<<p)=1011;

value =0;

Step 4:value<<p=0;

Step 5:n&(1UL<<p)|(value<<p)=1011;

n=(n&(1UL<<p))|(value<<p)=1011;

c++ function

int modify(int n,int pos,int value){

n=(n&(1UL<<p))|(value<<p);

return n;

}