按关键字排序.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"index.h"
//插入到keyorder以关键字排序的文件中
void keyInsert(char *pp1,index & a)
{fstream f2(pp1,ios::in|ios::out|ios::binary);
if(!f2) 
{cout<<"exit error!"<<endl;
exit(1);}
a.deletetag=0;
//将新结点插入到keyorder的尾部
f2.seekg(0,ios::end);
f2.write((char *)&a,d1);
f2.seekg(0,ios::end);
int yy1=f2.tellg()/d1;
index *A=new index[yy1];
f2.seekg(0,ios::beg);
f2.read((char*)A,yy1*d1);
//将所有的元素读出来排序
int work,cd;
index temp;
//用冒泡排序法排序
for(int pass=1;pass<yy1;pass++)
{work=1;
for (cd=0;cd<yy1-pass;cd++)
if(A[cd].key>A[cd+1].key)
{temp=A[cd];
A[cd]=A[cd+1];
A[cd+1]=temp;
work=0;}
if(work) break;
}
//再将它写入到keyorder中
f2.seekg(0,ios::beg);
f2.write((char*)A,d1*yy1);
f2.close();
}