power_of_two.cpp File Reference

Implementation to check whether a number is a power of 2 or not. More...

#include <iostream>
#include <cassert>

Include dependency graph for power_of_two.cpp:

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Namespaces
namespace	math
	for assert

Functions
int	math::power_of_two (int n)
	This function finds whether a number is power of 2 or not.
static void	test ()
	Self-test implementations.
void	user_input_test ()
	Take user input in the test cases (optional; currently commented)
int	main ()
	Main function.

Detailed Description

Implementation to check whether a number is a power of 2 or not.

This algorithm uses bit manipulation to check if a number is a power of 2 or not.

Algorithm

Let the input number be n, then the bitwise and between n and n-1 will let us know whether the number is power of 2 or not

For Example, If N= 32 then N-1 is 31, if we perform bitwise and of these two numbers then the result will be zero, which indicates that it is the power of 2 If N=23 then N-1 is 22, if we perform bitwise and of these two numbers then the result will not be zero , which indicates that it is not the power of 2

Note

This implementation is better than naive recursive or iterative approach.

Author

Neha Hasija

Rijul.S

Definition in file power_of_two.cpp.

Function Documentation

main()

int main

(

void

)

Main function.

Returns

0 on exit

Definition at line 99 of file power_of_two.cpp.

           {
    test(); // run self-test implementations
 
    // uncomment the line below to take user inputs
    //user_input_test();
 
    return 0;
}

test()

static void test ( )

static

Self-test implementations.

Returns

void

Definition at line 59 of file power_of_two.cpp.

                   {
    std::cout << "First case testing... \n"; // for n = 32 return 1
    assert(math::power_of_two(32) == 1);
    std::cout << "\nPassed!\n";
 
    std::cout << "Second case testing... \n"; // for n = 5 return 0
    assert(math::power_of_two(5) == 0);
    std::cout << "\nPassed!\n";
 
    std::cout << "Third case testing... \n"; // for n = 232 return 0
    assert(math::power_of_two(232) == 0);
    std::cout << "\nPassed!\n";
 
    std::cout << "\nAll test cases have successfully passed!\n";
}

user_input_test()

void user_input_test

(

)

Take user input in the test cases (optional; currently commented)

Returns

void

function call with

Parameters

n

Definition at line 79 of file power_of_two.cpp.

                       {
    int n = 0; // input from user
    
    std::cout << "Enter a number " << std::endl;
    std::cin >> n; 
 
    int result = math::power_of_two(n);
    if (result == 1) {
        std::cout << "Yes, the number " << n << " is a power of 2\n";
    }
    else { 
        std::cout << "No, the number " << n << " is not a power of 2\n";
    }
}