Binary search using pointer in c?

#include
#include
#include
void main()
{
int a[10]={1,2,3,10,11,13,16,21,46,73};
int mid,lower=0,upper=9,num,flag=1;
clrscr();
printf("enter the number to search");
scanf("%d",&num);
printf("\n the list of the data is");
printf("%-20s","\ndata);
for(num=0;num<=upper;num++)
printf("%3d",a[num]);
printf("%-20s","\nindexno");
for(num=0;num<=upper;num++)
printf("%3d",num);
for(mid=(lower+upper)/2;lower<=upper;mid=(lower+upper)/2)
{
if(a[mid]==num)
{
printf("the number is at position %d in array",mid);
flag=0;
break;
}
if(a[mid]>num)
upper=mid-1;
else
lower=mid+1;
}
if(flag)
printf("element is not present in the array");
getch();
}