急求高手！请教怎样用c产生6位随机密码，

急求高手！请问怎样用c产生6位随机密码，急！
如题，我刚学c不久，麻烦高手给一份源代码，学习一下。谢谢

srand((unsigned)time(NULL));
num = rand() % 100000000;

char *password= "0123456789abcd…xyz ";
char pass[6];
int id;
srand((unsigned)time(NULL));
for(int i = 0;i <6;i++)
{
id = rand() % 36;
pass[i] = password[id];
}
printf( "%s ",pass);