1 [cpp] view plain copy
  2 第一步：构建一个头文件（**.h）  
  3 [cpp] view plain copy
  4 #include<iostream>  
  5 #include<iomanip>  
  6 #include<fstream>  
  7 #include<string>  
  8 using namespace std;  
  9 class CStudentRec  
 10 {  
 11 public:  
 12     char chFlag;//标志，A表示正常，N表示空  
 13     char strName[20];//姓名  
 14     char strID[10];//学号  
 15     float fScore[3];//3门成绩  
 16     float fAve;//总平均分  
 17     CStudentRec(char *name,char *id,float score[]);  
 18     CStudentRec(){chFlag='N';};//默认构造函数  
 19     ~CStudentRec(){};//默认析构函数  
 20     void Input(void);  
 21     float Validate(void);//成绩数据的输入验证，返回正确值  
 22     void Print(bool isTitle=false);  
 23     friend ostream& operator<<( ostream& os,CStudentRec& stu);  
 24     friend istream& operator>>( istream& is,CStudentRec& stu);  
 25 };  
 26   
 27 CStudentRec::CStudentRec(char *name,char *id,float score[])  
 28 {  
 29     strncpy(strName,name,20);  
 30     strncpy(strID,id,10);  
 31     fAve=0;  
 32     for(int i=0;i<3;i++)  
 33     {  
 34         fScore[i]=score[i];  
 35         fAve+=fScore[i];  
 36     }  
 37     fAve=float(fAve/3.0);  
 38     chFlag='A';  
 39 }  
 40 void CStudentRec::Input(void)  
 41 {  
 42     cout<<"姓名：";  
 43     cin>>strName;  
 44     cout<<"学号：";  
 45     cin>>strID;  
 46     float fSum=0;  
 47     for(int i=0;i<3;i++)  
 48     {  
 49         cout<<"成绩"<<i+1<<":";  
 50         fScore[i]=Validate();  
 51         fSum+=fScore[i];  
 52     }  
 53     fAve=(float)(fSum/3.0);  
 54     chFlag='A';  
 55     getchar();  
 56 }  
 57 float CStudentRec::Validate(void)  
 58 {  
 59     int s;  
 60     char buf[80];  
 61     float res;  
 62     for(;;)  
 63     {  
 64         cin>>res;  
 65         s=cin.rdstate();  
 66         while(s)  
 67         {  
 68             cin.clear();  
 69             cin.getline(buf,80);  
 70             cout<<"非法输入，重新输入：";  
 71             cin>>res;  
 72             s=cin.rdstate();  
 73         }  
 74         if((res<=100.0)&&(res>=0.0))break;  
 75         else  
 76             cout<<"输入的成绩超过范围！请重新输入：";  
 77     }  
 78     return res;  
 79 }  
 80 void CStudentRec::Print(bool isTitle)  
 81 {  
 82     cout.setf(ios::left);  
 83     if(isTitle)  
 84         cout<<setw(20)<<"姓名："<<setw(10)<<"学号："<<"\t成绩1："<<"\t成绩2："<<"\t成绩3："<<"\t平均分："<<endl;  
 85     cout<<setw(20)<<strName<<setw(10)<<strID;  
 86     for(int i=0;i<3;i++)  
 87         cout<<"\t"<<fScore[i];  
 88     cout<<"\t"<<fAve<<endl;  
 89     getchar();  
 90 }  
 91 ostream& operator<<(ostream& os,CStudentRec& stu)  
 92 {  
 93     os.write(&stu.chFlag,sizeof(char));  
 94     os.write(stu.strName,sizeof(stu.strName));  
 95     os.write(stu.strID,sizeof(stu.strID));  
 96     os.write((char*)&stu.fScore,sizeof(float)*3);  
 97     os.write((char*)&stu.fAve,sizeof(float));  
 98     return os;  
 99 }  
100 istream& operator>>(istream& is,CStudentRec& stu)  
101 {  
102     char name[20],id[10];  
103     is.read(&stu.chFlag,sizeof(char));  
104     is.read(name,sizeof(name));  
105     is.read(id,sizeof(id));  
106     is.read((char*)stu.fScore,sizeof(float)*3);  
107     is.read((char*)&stu.fAve,sizeof(float));  
108     strncpy(stu.strName,name,sizeof(name));  
109     strncpy(stu.strID,id,sizeof(id));  
110     return is;  
111 }  
112   
113 class CStuFile  
114 {  
115 public:  
116     CStuFile(char* filename);  
117     ~CStuFile();  
118     void Add(CStudentRec stu);  
119     int Seek(char* id,CStudentRec &stu);  
120     int List(int nNum=-1);  
121 private:  
122     char* strFileName;  
123 };  
124 CStuFile::CStuFile(char* filename)  
125 {  
126     strFileName=new char[strlen(filename)+1];  
127     strcpy(strFileName,filename);  
128 }  
129 CStuFile::~CStuFile()  
130 {  
131     if(strFileName)delete []strFileName;  
132 }  
133 void CStuFile::Add(CStudentRec stu)  
134 {  
135     fstream file(strFileName,ios::out|ios::app|ios::binary);  
136     file<<stu;  
137     file.close();  
138 }  
139 int CStuFile::Seek(char* id,CStudentRec& stu)  
140 {  
141     int nRec=-1;  
142     fstream file(strFileName,ios::in|ios::_Nocreate);  
143     if(!file)  
144     {  
145         cout<<"文件"<<strFileName<<"不能打开！\n";  
146         return nRec;  
147     }  
148     int i=0;  
149     while(!file.eof())  
150     {  
151         file>>stu;  
152         if((strcmp(id,stu.strID)==0)&&(stu.chFlag!='N'))  
153         {  
154             nRec=i;break;  
155         }  
156         i++;  
157     }  
158     file.close();  
159     return nRec;  
160     getchar();  
161 }  
162 int CStuFile::List(int nNum)  
163 {  
164     fstream file(strFileName,ios::in|ios::_Nocreate);  
165     if(!file)  
166     {  
167         cout<<"文件"<<strFileName<<"不能打开！\n";  
168         return 0;  
169     }  
170     int nRec=0;  
171     if((nNum==-1)||(nNum>0))  
172     {  
173         cout.setf(ios::left);  
174         cout<<setw(6)<<"记录"<<setw(20)<<"姓名"<<setw(10)<<"学号"<<"\t成绩1\t成绩2\t成绩3\t平均分"<<endl;  
175     }  
176     while(!file.eof())  
177     {  
178         CStudentRec data;  
179         file>>data;  
180         if(data.chFlag=='A')  
181         {  
182             nRec++;  
183             if((nNum==-1)||(nRec<=nNum))  
184             {  
185                 cout.setf(ios::left);  
186                 cout<<setw(6)<<nRec;  
187                 data.Print();  
188             }  
189         }  
190     }  
191     file.close();  
192     return nRec;  
193 }  
194 [cpp] view plain copy
195 第二部：创建一个.cpp文件  
196 [cpp] view plain copy
197 #include<iostream>  
198 #include"**.h"  
199 CStuFile theStu("student.txt");  
200 void AddTo(int nNum)  
201 {  
202  CStudentRec stu;  
203  for(int i=0;i<nNum;i++)  
204  {  
205   cout<<"请输入第"<<i+1<<"记录:"<<endl;  
206   stu.Input();  
207   theStu.Add(stu);  
208  }  
209 }  
210 void main()  
211 {  
212  AddTo(3);  
213  theStu.List();  
214  CStudentRec one;  
215  if(theStu.Seek("21050102",one)>=0)  
216   one.Print(true);  
217  else  
218   cout<<"没有找到！\n";  
219  theStu.List();  
220  getchar();  
221 }  
222 [cpp] view plain copy
223 ok