Binary to Hexadecimal conversion - C++ Program

#include<iostream>
#define MAX 1000
using namespace std;

int main()
{
        char binnum[MAX], hexa[MAX];
        int temp;
        long int i=0,j=0;  
        cout<<"\n Enter Binary Number : ";
        cin>>binnum;
        while(binnum[i])
        {
                binnum[i] = binnum[i] -48;
                ++i;
        }
        --i;
        while(i-2>=0)
        {
                temp =  binnum[i-3] *8 + binnum[i-2] *4 +  binnum[i-1] *2 + binnum[i] ;
                if(temp > 9)
                        hexa[j++] = temp + 55;
                else
                        hexa[j++] = temp + 48;
                i=i-4;
        }
        if(i ==1)
                hexa[j] = binnum[i-1] *2 + binnum[i] + 48 ;
        else if(i==0)
                hexa[j] =  binnum[i] + 48 ;
        else
                --j;
        cout<<"\n Binary Number to Hexadecimal Number : ";
        while(j>=0)
        {
                cout<<hexa[j--];
        }
        return 0;
}