缓存清不已，不知道为什么

缓存清不了，不知道为什么。
#include<iostream.h>
#include<stdlib.h>
#include<time.h>
#include<conio.h>
int main(){
int a,char b;
  srand((unsigned)time(0));
  do{
  for(int i=0;i<1;i++){
double ran_num=rand()%10;
  do{
cout<<"please enter a number between 1 to 10.\n"; 
  cin.clear();
  cin.sync(); 
cin>>a;
if(a==0){
cout<<"data type error!\n";
b='y';
continue;}
if(a<=0||a>=10){
cout<<"input a number between 1 to 10!\n";
b='y';
continue;}
if(a!=ran_num&&a>ran_num){
cout<<"please input a lesser number\n";}
if(a!=ran_num&&a<ran_num){
cout<<"please input a lager number\n";}
}while(a!=ran_num);
cout<<"Gongratulation!\n";
}
  do{
cout<<"\nContinue(yes or no)?\n";
b=getche();
  }while(b!='y'&&b!='n');
  }while(b=='y');
}


各位大哥可以复制下来，到vc6中运行下试试。由于我才学c++，有很多问题啊~~~~
这个是个简单的猜数游戏，我想控制不能输入字母，但一旦输入字母就会出现无限循环的情况，应该是缓存没清,但我写了cin.clear();cin.sync();的呀，真不知道为什么了~~~~~；还有就是当猜对时，要输入“y”，才会出现 “Gongratulation!”，然后就立马重复游戏了......这个顺序不对啊，应该是出现“Gongratulation!”再问“Continue(yes or no)?”，输入“y”之后才继续游戏啊......
麻烦大家帮帮忙吧，我真不知道是哪出问题了~~~~~谢谢拉~~~~~

[解决办法]

C/C++ code

int main(){    int a,char b;    srand((unsigned)time(0));    do{            double ran_num=rand()%10;            do{                cout<<"please enter a number between 1 to 10.\n";                                  cin>>a;                if (cin.bad())                {                    cin.clear();                    cin.sync();                    continue;                }                 else                {                    if(a==0){                        cout<<"data type error!\n";                        b='y';                        continue;                    }                    if(a<=0||a>=10){                        cout<<"input a number between 1 to 10!\n";                        b='y';                        continue;                    }                    if(a!=ran_num&&a>ran_num){                        cout<<"please input a lesser number\n";}                    if(a!=ran_num&&a<ran_num){                        cout<<"please input a lager number\n";}                }            }while(a!=ran_num);            cout<<"Gongratulation!\n";        do{            cout<<"\nContinue(yes or no)?\n";            b=getch();        }while(b!='y'&&b!='n');    }while(b=='y');}
[解决办法]
你这个嵌套循环太多了   很容易出错的，
[code=C/C++][/code]
#include<iostream.h>
#include<stdlib.h>
#include<time.h>
#include<stdio.h>
#include<conio.h>
void main()
{  unsigned int a;
char b;
srand((unsigned)time(0));
double ran_num=rand()%10;
do{
b='c';          //将b赋值一个非Y/N
cout<<"please enter a number between 1 to 10.\n"; 
cin>>a;
if(a==0)
cout<<"data type error!\n";
if(a>=10)
cout<<"input a number between 1 to 10!\n";
if(a!=ran_num&&a>ran_num){
cout<<"please input a lesser number\n";}
if(a!=ran_num&&a<ran_num){
cout<<"please input a lager number\n";}
if (a==ran_num)
cout<<"Gongratulation!\n"; 
 

cout<<"\nContinue(yes or no)?\n";
cin>>b;}
while(b=='y');
}