text1.cpp

这个程序是定位文件的程序

#include<iostream.h>
#include<iomanip.h>
#include<fstream.h>
#include<string.h>
class CStudent
{
private:
	char strName[10];
	char strID[10];
	float fScore;
public:
	CStudent(char* name,char* id,float score=0);
	void print();
	friend ostream& operator<<(ostream& os,CStudent& stu);
	friend istream& operator>>(istream& is,CStudent& stu);
};

CStudent::CStudent(char* name,char* id,float score)
{
	strncpy(strName,name,10);
	strncpy(strID,id,10);
	fScore=score;
}

void CStudent::print()
{
	cout<<endl<<"学生信息如下："<<endl;
	cout<<"姓名："<<strName<<endl;
	cout<<"学号："<<strID<<endl;
	cout<<"成绩："<<fScore<<endl;
}

ostream& operator<<(ostream& os,CStudent& stu)
{
	os.write(stu.strName,10);
	os.write(stu.strID,10);
	os.write((char*)&stu.fScore,4);
	return os;
}

istream& operator>>(istream& is,CStudent& stu)
{
	char name[10],id[10];
	is.read(name,10);
	is.read(id,10);
	is.read((char*)&stu.fScore,4);
	strncpy(stu.strName,name,10);
	strncpy(stu.strID,id,10);
	return is;
}

void main()
{
	CStudent stu1("mawentao","99001",88);
	CStudent stu2("liming","99002",93);
	CStudent stu3("wangfang","99003",89);
	CStudent stu4("yangyang","99004",90);
	CStudent stu5("dingning","99005",80);
	fstream file1;
	file1.open("student.doc",ios::out|ios::in|ios::binary);
	file1<<stu1<<stu2<<stu3<<stu4<<stu5;
	CStudent* one=new CStudent("","");
	const int size=24;
	file1.seekp(size*4);file1>>*one;one->print();
	file1.seekp(size*1);file1>>*one;one->print();
	file1.seekp(size*2,ios::cur);file1>>*one;one->print();
	file1.close();
	delete one;
}