Binary inversion of number and converting decimal to Binary in C++

Code to do binary inversion of a number in C++

#include <iostream>
using namespace std;
int main() {
    unsigned int ip_num,op_num,i=0,tmp;
    cin>>ip_num;
    tmp = ip_num;
    while(tmp!=0)
    {
        tmp = tmp>>1;
        i++;
    }
    //i = 8-i;
    //i = 16 -i;
    i = 32-i;
    op_num = ~ip_num;
    op_num = op_num<<i;
/* Any bit value right shifted should be re-initialised to zero */
    //op_num = op_num&255;
    //op_num = op_num&65535;
    op_num = op_num&4294967295;
    op_num = op_num>>i;
    cout<<op_num;
return 0;
}

Code to display Binary value of a number in C++ upto 16 binary digit.

void toBin(unsigned int n){
    int i=0;
    //while(n && i!=16){

       // int res = n&32768;
        if(res)
            cout<<1;
        else
            cout<<0;
        n = n<<1;
        i++;
    }
    cout<<endl;
}