怎样用C程序将10进制数转换成16进制?

#include"stdio.h"
main()
{ int x;
scanf("%d",&x);
printf("%x",x);
}
==================================
#include "stdio.h"
main()
{ int x,i=0,y,j;
char a[80];
scanf("%d",&x);
y=x;
while(x>0)
{ switch (x%16)
{ case 1: a[i]='1';break;
case 2: a[i]='2';break;
case 3: a[i]='3';break;
case 4: a[i]='4';break;
case 5: a[i]='5';break;
case 6: a[i]='6';break;
case 7: a[i]='7';break;
case 8: a[i]='8';break;
case 9: a[i]='9';break;
case 10: a[i]='A';break;
case 11: a[i]='B';break;
case 12: a[i]='C';break;
case 13: a[i]='D';break;
case 14: a[i]='E';break;
case 15: a[i]='F';break;
}
x=x/16;
i++;<