/* C++ Program - Binary to Octal */
		
#include<iostream.h>
#include<conio.h>
void main()
{
	clrscr();
	long int binnum, rem, quot;
	int octnum[100], i=1, j;
	cout<<"Enter any binary number : ";
	cin>>binnum;
	quot=binnum;
	while(quot!=0)
	{
		octnum[i++]=quot%8;
		quot=quot/8;
	}
	cout<<"Equivalent octal value of "<<binnum<<" :\n";
	for(j=i-1; j>0; j--)
	{
		cout<<octnum[j];
	}
	getch();
}

Output
Enter any binary number :11
Equivalent octal value of 11 :
13