Conversion of decimal number to a binary number in C++

#include<iostream.h>

#include<math.h>
#include<conio.h>
#include<stdlib.h>

void main()
{
int dec_num;
int bin_digits;
int *bi;
int index,i;
int repeat;

clrscr();

do
{
cout<<"\n"<<"Enter the decimal number ";
cin>>dec_num;
bin_digits=(log10(dec_num)/log10(2))+1;

bi=new int[bin_digits];
index=0;

while(dec_num > 0)
{
bi[index]=dec_num % 2;
index++;
dec_num=dec_num / 2;
}

for(i=bin_digits-1;i>=0;i--)
cout<<bi[i];

delete[] bi;
cout<<"\n"<<"Repeat? Press 1 ";
cin>>repeat;
}while(repeat == 1);

exit(0);
}

OUTPUT: