C++ program to convert binary to Hexadecimal number

Here is a C++ program to convert binary to hexadecimal. Here are the different methods to convert binary to hexadecimal like using recursion.
How to convert binary to hexadecimal (base 2 to base 16).
To convert binary to hexadecimal just take four bits and convert it in decimal number .For example let us convert binary number (10101011)₂ to hexadecimal. Note if the number is greater than 9 we write alphabets A,B,C,D,E,F in place of 10,11,12,13,14,15.
(1011)₂ decimal equivalent is 11 so write B
(1010)₂ decimal equivalent is 10 so write A.
Thus equivalent of hexadecimal number is (AB)₁₆.

Method 1 : C++ program to convert binary to hexadecimal

#include<iostream>
#include<math.h>
using namespace std;
int main()
{
    int i,temp=0,hexa[20],rem,num;
    cout<<"Enter the number in binary ";
    cin>>num;
    cout<<"Hexadecimal eqivalent ";
    for(i=0;num>0;i++)
    {
        for(int y=0;y<4;y++)
        {
             rem=num%10;
             num/=10;
             temp+=rem*pow(2,y);
       }
       hexa[i]=temp;
       temp=0;
    }
    while(i>0)
    {
        i--;
        if(hexa[i]>9)
            cout<<char(55+hexa[i]);
        else
            cout<<hexa[i];
    }
    return 0;
}

Method 2 : C++ program to convert binary to hexadecimal using recursion

#include<iostream>
#include<math.h>
using namespace std;
int deci(int n,int i)
{
    if(n==0)
        return 0;
    return (n%10)*pow(2,i)+deci(n/10,i+1);
}
void hex(int n)
{
    int hexa;
    if(n==0)
        return;
    hex(n/10000);
    hexa=deci(n%10000,0);
    if(hexa>9)
        cout<<char(55+hexa);
    else
        cout<<hexa;
}
int main()
{
    int num;
    cout<<"Enter Binary number : ";
    cin>>num;
    cout<<"Hexadecimal equivalent : ";
    hex(num);
    return 0;
}

Method 3 : C++ program to convert binary to hexadecimal using function

#include<iostream>
#include<math.h>
#include<string.h>
using namespace std;
void hex(int num)
{
    int i,temp=0,hexa[20],rem;
    cout<<"Hexadecimal eqivalent ";
    for(i=0;num>0;i++)
    {
        for(int y=0;y<4;y++)
        {
             rem=num%10;
             num/=10;
             temp+=rem*pow(2,y);
       }
       hexa[i]=temp;
       temp=0;
    }
    while(i>0)
    {
        i--;
        if(hexa[i]>9)
            cout<<char(55+hexa[i]);
        else
            cout<<hexa[i];
    }
}
int main()
{
    int num;
    cout<<"Enter the number in binary ";
    cin>>num;
    hex(num);
    return 0;
}

Method 4 : C++ program to convert binary to hexadecimal and store it as string

#include<iostream>
#include<math.h>
#include<string.h>
using namespace std;
int main()
{
    char bin[40],hex[10];
    int i=0,z=0,y=0,temp=0;
    cout<<"Enter the number in binary ";
    cin>>bin;
    z=strlen(bin)-1;
    while(z>=0)
    {
        for(y=0;y<4&&z>=0;y++)
             temp+=(bin[z--]-48)*pow(2,y);
        if(temp>9)
            hex[i++]=temp+55;
        else
            hex[i++]=temp+48;
        temp=0;
    }
    hex[i]='\0';
    strrev(hex);
    cout<<"Hexadecimal equivalent "<<hex;
    return 0;
}