Rounding up a number to power of 2 < number

Using concept of "n&(n-1)" makes value = 0 if n is number with power of 2

#include <stdio.h>
int nextPwrOf2(int num)
{
     do
     {
 

Rounding up a number to next power of 2.

By using the concept of filling all the bits by 1 using shift operation. 
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#include<stdio.h>

int main()

{

      unsigned int n =1;

      n |= n >> 1;

      n |= n >> 2;