c program Convert a decimal number to hexadecimal

#include<stdio.h>
main()
{
int r,num,a[10],i=0,j;
clrscr();
printf("Enter a Decimal number\n");
scanf("%d",&num);
while(num>0)
{
r=num%16;
a[i]=r;
num=num/16;
i++;
}
printf("hex number is=:");
for(j=i-1;j>=0;j--)
{
switch(a[j])
{
case 10:
printf("A");
break;
case 11:
printf("B");
break;
case 12:
printf("C");
break;
case 13:
printf("D");
break;
case 14:
printf("E");
break;
case 15:
printf("F");
break;
default :
printf("%d",a[j]);
break;
}
}
printf("\n");
getch();
}