maindelete.cpp

该程序实现了用文件记录变长字节流

#include<iostream.h>
#include<fstream.h>
#include<stdlib.h>
#include<iomanip.h>
#include<string.h>
#include"mainfile.h"
bool maindelete(char *p1,char *p2,element a)//is need a & remenber to look up.
{fstream f1(p1,ios::in|ios::out|ios::binary);
if (!f1){cerr<<"exit error!"<<endl;
exit(1);
}
fstream f2(p2,ios::in|ios::out|ios::binary);
if (!f1) {cerr<<"exit error!"<<endl;
exit(1);
}
int j;
int va1=a.key/10;
f2.seekg(0,ios::end);
int len=f2.tellg()/b3;
indexnode *A=new indexnode[len];
f2.seekg(0,ios::beg);
f2.read((char *)A,len*b3);
int i=0;
int rr;
for(;i<len;i++)
if(A[i].value==va1)
break;
team pt;
if(i<len)
{int k=A[i].num;
f1.seekg(k*b2,ios::beg);
f1.read((char *)&pt,b2);
for(j=0;j<10;j++)
{if(pt.data[j].key==a.key&&pt.data[j].deletetag==0)
break;
}
if(j<10)
{pt.data[j].deletetag=1;
if(pt.data[j].next!=-1) 
{rr=pt.data[j].next; 
pt.data[rr].deletetag=1;}
cout<<pt.data[j].key<<" "<<pt.data[j].name<<endl;
f1.seekg(A[i].num*b2,ios::beg);
f1.write((char*)&pt,b2);
return true;
}
else
{cout<<"不存在该元素!"<<endl;
return false;
}
}
else
{cout<<"不存在该元素!"<<endl;
return false;
}}