binary,octal,hexadecimal 1 using function

#include<stdio.h>
#include<conio.h>
main()
{
int a[16],i,j,x,b,c,d,z;
char h[16]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
clrscr();
printf("\n conversion menu");
printf("\n1. binary ");
printf("\n2. octal");
printf("\n3. hexadecimal");
printf("\n==============================================================\n");
printf("enter your choice");
scanf("%d",&x);
printf("\n==============================================================\n");
printf("enter a number\n");
scanf("%d",&b);
switch(x)
{
case 1:
z=2;
break;
case 2:
z=8;
break;
case 3:
z=16;
break;
default :
printf("no choice avaiable\n");
getch();
exit(0);
}
//conversion process
for(i=0;b>0;i++)
{
a[i]=b%z;
b=b/z;
}
printf("number after conversion is:\n");
for(i--;i>=0;i--)
{
printf("%c",h[a[i]]);
}
getch();
return 0;
}