C++ program to check if binary representation of a number is palindrome

For a non-negative number x, print Yes if the binary representation of x is a palindrome else print No in C++. The binary representation of a number with leading 0’s will not be considered for checking palindrome.

What are a binary representation and a palindrome?

A binary number is a number that uses only 0 and 1 in the base 2 numeral system and a palindrome is a string, phrase, or a number that remains the same even if its digits or characters are reversed.

Algorithm:

1) The first step is to make a function check_palindrome in which first we find the number of bits in x using sizeof() and set left positions as 1 and right positions as n.

2)The next step is, while left ‘x’ is smaller than right ‘y’:
->Return false if the bit at x is not equal to y and keep incrementing x and decrementing y.

3) If we come to this step it means there was no mismatching bit.

The expression “x &(1<<(a-1))” gives a value zero if the a’th bit from the right is not set and non zero value if it is set.

Example:

If the binary representation of a number is 1001, then it is a palindrome and if it is 1100, then it is not a palindrome.

Program to check if the binary representation of a number is a palindrome in C++

#include<bits/stdc++.h>
using namespace std;

// function returns true if a'th bit is set
// and false if it is not set
bool bit_set(int x,int a)
{
    return (x & (1<<(a-1))) ? true : false;
}


// function returns true if p is a palindrome
// and false if it is not
bool check_palindrome(int p)
{
    int x=1;                // set the left position
    int y=sizeof(int)*8;    // set the right position

    //comparing bits
    while(x<y)
    {
        if(bit_set(p,x)!=bit_set(p,y))
            return false;
        x++;
        y--;
    }
    return true;
}
int main()
{
    int p= 1 <<15+1<<16;
    cout<<check_palindrome(p)<<endl;
    p=1 <<31+1;
    cout<<check_palindrome(p)<<endl;
}

Output:
1
1