about "cout "

#include <iostream.h>
#include <stdlib.h>
#include <stdio.h>
#include <memory.h>

int main()
{
char buf[10] ;
memset(buf,128,sizeof(buf)) ;

cout << endl << hex << buf << endl ;

for(int j =0 ;j<10 ;j++)
{
cout << " " << hex << (unsigned char) buf[j] ;
}

cout << endl ;

for(int i =1 ;i<10 ;i++)
{
printf(" %x",(unsigned char)buf[i]);
}


return 0 ;
}


printf能输出 80 80 80 80 80 ....
怎样使用cout 输出呢？