电子词典如下，有点不懂

#include<fstream>
#include<iostream>
#include<string>
using namespace std;
string e[8000],c[8000];
int wordsnum=0;
int chazhao(int low,int high,string k);
int main()
{

 string key;      //查询关键词   
    //将文件中的数据读入到对象数组中   
    ifstream infile("dictionary.txt",ios::in);  //以输入的方式打开文件   
    if(!infile)       //测试是否成功打开   
    {  
        cerr<<"open error!"<<endl;  
        exit(1);  
    }  
    while (!infile.eof())  
    {  
        infile>>e[wordsnum]>>c[wordsnum];  
        ++wordsnum;  
    }  
    infile.close();
	do{
	int n, low=0,high=wordsnum-1;
  cout<<"请输入要查的单词(0000结束)"<<endl;
  cin>>key;
  if(key=="0000")
	  break;
  else{
	   n=chazhao(low,high,key);
  if(n==-1)
	  cout<<"查无此词"<<endl;
 else
     cout<<key<<"的意思是： "<<c[n]<<endl<<endl;
  }
	}while(1);
		cout<<"欢迎下次再来"<<endl<<endl;
return 0;
}
int chazhao(int low,int high,string k){
  int i;
  while(low<=high){
	  i=(low+high)/2;
	  if(e[i]==k)
    return i;
	  else{
		  if(e[i]>k)
			  high=i-1;
		  if(e[i]<k)
			  low=i+1;
	 }
  }
 
   return -1;

}

运行结果：