{d=SeqDelete(A, s, x);
if(d)
ofs.write((char*)A, (s-1)*b2);
else
ofs.write((char*)A,s*b2);
break;//处理完最后一个数据块时退出while(1)循环
}}
delete [] A;
ifs.close();
ofs.close();
remove(fn2);
rename("temp", fn2);
if(d) return true; else return false;
}
//从由fn2指针所表示的索引有序文件中
//查找关键字为x.key的索引项并由x带回
template
bool InFile::IFSearch(char* fn2, T& x)
{ifstream ifs(fn2,ios::in|ios::binary);
//以输入方式打开由fn2指针所表示的索引有序文件
if(!ifs)
{cerr< ifs.seekg(0,ios::end);
int b2=sizeof(T);
int n=ifs.tellg()/b2;
ifs.seekg(0);
int low=0, high=n-1;
while(low<=high)
{ //计算区间中点元素的下标
int mid=(low+high)/2;
//从文件中读入区间中点元素并赋给tm
T tm;
ifs.seekg(mid*b2);
ifs.read((char*)&tm,b2);
//查找成功后由x带回查找到的索引项并返回真
if(x.key==tm.key) {x=tm;
ifs.close();
return true;}
//在左子表中继续查找
else if(x.key high=mid-1;
//在右子表中继续查找
else low=mid+1;}
ifs.close();
return false;}//查找失败返回假
#endif // !defined(AFX_INDEX_H__68B93657_9E7D_4BE5_9259_4780B68E38BD__INCLUDED_)
调用如下
[cpp]
#include "stdafx.h"
#include
#include
#include
#include
#include "Index.h"
//索引文件的类实现的测试
void main()
{cout<<"运行结果:\n";
//定义保存记录的数组a并初始化
ElemType a[15]={{13,"li"},{18,"liu"},{17,"wphp"},{37,"menrm"},
{8,"ytong"},{22,"zhua"},{24,"push"},{48,"qian"},{34,"tang"},
{57,"shdm"},{55,"kang"},{30,"liuli"},{25,"qiaoh"},
{31,"dukun"},{17,"haiang"}};
//定义保存记录关键字的数组b并初始化
KeyType b[16]={12,18,15,32,6,23,21,48,36,57,45,29,25,38,14,9};
//定义主文件和索引文件的名字，并由字符指针p1和p2所指向
char *p1=".\\HFile1.dat",*p2=".\\HFile1.idx";
int m;//记录个数
InFile myfile;
//利用键盘输入操作主文件、索引文件的插入、删除和查找
while(1) {
cout< cout<<"1---向主文件插入若干记录"< cout<<"2---从主文件中删除若干记录"< cout<<"3---从主文件中查找若干记录"< cout<<"4---输出主文件fn1"< cout<<"5---输出索引文件fn2"< cout<<"6---结束运行"< char ch;
cout<<"请输入你的选择(1-6): ";cin>>ch;
switch (ch)
{case '1':cout<<"输入待插入记录个数m:";
cin>>m;myfile.MFAppend(p1,p2,a,m);break;
case '2':cout<<"输入待删除记录个数m:";
cin>>m;myfile.MFDelete(p1,p2,b,m);break;
case '3':cout<<"输入待查找记录个数m:";
cin>>m;myfile.MFSearch(p1,p2,b,m);break;
case '4':myfile.PrintMainFile(p1);break;
case '5':myfile.PrintIndexFile(p2);break;
case '6':return;
default:cout<<"输入选择错误,请重输!"< }}}
效果如下
 
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