简易的学生成绩管理系统（C++实现）

最近浅显的学习了C++的基础知识，想来练练手，于是就用单链表写了最经典的小项目，存粹学习，所以就在控制台下写了，写的有点简陋，码了大概400多行。
下面上代码：
  1 #include <cstdlib>
  2 #include <iostream>
  3 #include <string>
  4 using namespace std;
  5 
  6 #define null NULL
  7 
  8 class student
  9 {
 10     private:
 11         friend class studentMessage;
 12         student *next; //节点指针
 13         string name; //学生姓名
 14         int age; //年纪
 15         int id; //学号
 16         double score[3]; //三科成绩
 17         double total; //总分
 18         double average; //平均成绩
 19     public:
 20         student(string _name,int _age,int _id,double *_score)
 21         {
 22             name = _name;
 23             age = _age;
 24             id = _id;
 25             score[0] = _score[0];
 26             score[1] = _score[1];
 27             score[2] = _score[2];
 28             total = score[0]+score[1]+score[2];
 29             average = total/3;
 30             next = NULL;
 31         }
 32         student() //为studentMessage初始化头结点用
 33         {
 34             name = "null";
 35             age = 0;
 36             id = 0;
 37             score[0]=score[1]=score[2]=0;
 38             total = 0;
 39             average = 0;
 40             next = NULL;
 41         }
 42         ~student(){}
 43         void swap(student*);
 44 };
 45 
 46 
 47 void student::swap(student *q)
 48 {
 49     string _name;
 50     int _age,_id;
 51     double _score[3],_total,_average;
 52     
 53     _name = name;
 54     name = q->name;
 55     q->name = _name;
 56     
 57     _age = age;
 58     age = q->age;
 59     q->age = _age;
 60     
 61     _id = id;
 62     id = q->id;
 63     q->id = _id;
 64     
 65     _score[0] = score[0];
 66     score[0] = q->score[0];
 67     q->score[0] = _score[0];
 68     
 69     _score[1] = score[1];
 70     score[1] = q->score[1];
 71     q->score[1] = _score[1];
 72     
 73     _score[2] = score[2];
 74     score[2] = q->score[2];
 75     q->score[2] = _score[2];
 76     
 77     _total = total;
 78     total = q->total;
 79     q->total = _total;
 80     
 81     _average = average;
 82     average = q->average;
 83     q->average = _average;
 84 }
 85 
 86 
 87 
 88 
 89 
 90 
 91 class studentMessage
 92 {
 93     private:
 94       student *first; //头指针
 95       int num; //信息中的学生人数
 96     public:
 97         studentMessage()
 98         {
 99             num = 0; //初始化学生人数为0
100             first = new student;  //初始化头结点
101         }
102         ~studentMessage(){delete first;}
103 
104         /*管理系统常规操作*/
105         void Insret(void); //插入
106         void Display(void); //显示
107         void Delete(void); //删除
108         void Search(void); //搜索
109         void Change(void); //改动
110         void sortByLesson1(void); //按成绩一来排序
111         void sortByLesson2(void); //按成绩二来排序
112         void sortByLesson3(void); //按成绩三来排序
113         void sortByTotal(void); //按总分来排序
114         void SearchByid(void); //按照学号查找
115         void SearchByname(void); //按照姓名查找
116         int menu(void); //初始的菜单
117         void clear(void); //清空列表
118 };
119 
120 
121 int studentMessage::menu(void)
122 {
123     int ch;
124     cout<<"**********************************************************************"<<endl;
125     cout<<"======================================================================"<<endl;
126     cout<<"***************************学生成绩管理系统***************************"<<endl;cout<<endl;
127     cout<<"1.显示所有学生成绩"<<endl;
128     cout<<"2.添加学生信息"<<endl;
129     cout<<"3.查询学生信息"<<endl;
130     cout<<"4.修改学生信息"<<endl;
131     cout<<"5.删除最下面一个学生信息"<<endl;
132     cout<<"6.删除所有信息"<<endl;
133     cout<<"0.退出系统"<<endl;cout<<endl;
134     cout<<"********************Copyright@ By Jeaven Wong**************************"<<endl;
135     cout<<"======================================================================="<<endl;
136     cout<<"***********************************************************************"<<endl;
137     cin >> ch;
138     cout<<"\n\n\n"<<endl;
139     return ch;
140 }
141 
142 
143 
144 //插入
145 void studentMessage::Insret(void)
146 {
147     string name;
148     int age;
149     int id;
150     double score[3];
151     cout<<"请输入学生姓名: ";
152     cin>>name;
153     cout<<"请输入学生年龄: ";
154     cin>>age;
155     cout<<"请输入学生学号: ";
156     cin>>id;
157     cout<<"下面请输入学生三门课程成绩: ";
158     cout<<endl;
159     cout<<"请输入第一门课的成绩: ";cin>>score[0];
160     cout<<"请输入第二门课的成绩: ";cin>>score[1];
161     cout<<"请输入第三门课的成绩: ";cin>>score[2];
162     cout<<endl;
163 
164     
165     student *newstu = new student(name,age,id,score);
166     student *p = first;
167     while(p->next != NULL)
168     {
169         p = p->next;
170     }
171     p->next = newstu;
172     newstu->next = null;
173     num++;
174 }
175 
176 
177 
178 void studentMessage::Display(void)
179 {
180     if(num == 0)
181     {
182         cout<<"当前记录中无学生..."<<endl;
183     }
184         
185     else
186     {
187         student *p = first->next;
188         while(p != null)
189         {
190             cout<<"姓名:"<<p->name<<"  ";
191             cout<<"年龄:"<<p->age<<"  ";
192             cout<<"学号:"<<p->id<<"  ";
193             cout<<"三门课程成绩: "<<p->score[0]<<" "<<p->score[1]<<" "<<p->score[2]<<"  ";
194             cout<<"总分:"<<p->total<<"  ";
195             cout<<"平均分:"<<p->average<<endl;
196             p = p->next;
197         }
198     }    
199 }
200 
201 
202 void studentMessage::Delete(void)
203 {
204     student *p = first;
205     student *pre = first;
206     while(p->next != NULL)
207     {
208         pre = p;
209         p = p->next;
210     }
211     pre->next = NULL;
212     delete p;
213     num--;
214 }
215 
216 
217 void studentMessage::Search(void)
218 {
219     int temp = 0;
220     cout<<"请输入查找的条件，有如下选项..."<<endl;
221     cout<<"按照学号查找（请输入【1】） 按照姓名查找（请输入【2】）"<<endl;
222     cin>>temp;
223     switch(temp)
224     {
225         case 1: SearchByid(); break;
226         case 2: SearchByname(); break;
227         default: cout<<"输入有误..."<<endl;
228     }
229 }
230 
231 void studentMessage::SearchByid(void)
232 {
233     int _id;
234     int flag = 0;
235     cout<<"请输入待查找学生的学号：";
236     cin >> _id;
237     student *p = first->next;
238     while(p != null)
239     {
240         if(p->id == _id)
241         {
242             flag = 1;
243             cout<<"下面是查找匹配结果："<<endl;
244             cout<<"姓名:"<<p->name<<"  ";
245             cout<<"年龄:"<<p->age<<"  ";
246             cout<<"学号:"<<p->id<<"  ";
247             cout<<"三门课程成绩: "<<p->score[0]<<" "<<p->score[1]<<" "<<p->score[2]<<"  ";
248             cout<<"总分:"<<p->total<<"  ";
249             cout<<"平均分:"<<p->average<<endl;    
250         } 
251         p = p->next;
252     }
253     if(flag == 0)
254     {
255         cout<<"抱歉，记录中没有查找匹配项..."<<endl;
256     }
257 }
258 
259 void studentMessage::SearchByname(void)
260 {
261     string _name;
262     int flag = 0;
263     cout<<"请输入待查找的学生姓名: ";
264     cin >> _name;
265     student *p = first->next;
266     while(p != null)
267     {
268         if(p->name == _name)
269         {
270             flag = 1;
271             cout<<"下面是查找匹配结果："<<endl;
272             cout<<"姓名:"<<p->name<<"  ";
273             cout<<"年龄:"<<p->age<<"  ";
274             cout<<"学号:"<<p->id<<"  ";
275             cout<<"三门课程成绩: "<<p->score[0]<<" "<<p->score[1]<<" "<<p->score[2]<<"  ";
276             cout<<"总分:"<<p->total<<"  ";
277             cout<<"平均分:"<<p->average<<endl;    
278         }
279         p = p->next;
280     }
281     
282     if(flag == 0)
283     {
284         cout<<"抱歉，记录中没有查找匹配项..."<<endl;
285     }
286 }
287 
288 
289 
290 void studentMessage::Change(void)
291 {
292     string _name;
293     int flag = 0,temp;
294     int _id,_age;
295     int course = 0;
296     cout<<"请输入需要改动信息的学生的姓名: ";
297     cin >> _name;
298     student *p = first->next;
299     while(p != null)
300     {
301         if(p->name == _name)
302         {
303             flag = 1;
304             cout<<"该学生当前信息如下："<<endl;
305             cout<<"姓名:"<<p->name<<"  ";
306             cout<<"年龄:"<<p->age<<"  ";
307             cout<<"学号:"<<p->id<<"  ";
308             cout<<"三门课程成绩: "<<p->score[0]<<" "<<p->score[1]<<" "<<p->score[2]<<"  ";
309             cout<<"总分:"<<p->total<<"  ";
310             cout<<"平均分:"<<p->average<<endl;    
311             cout<<"请指明哪一项需要修改..."<<endl;
312             cout<<"修改学号（输入【1】） 修改年龄（输入【2】）修改成绩（输入【3】）"<<endl;
313             cin >> temp;
314             switch(temp)
315             {
316                 case 1: 
317                     {
318                         cout<<"请输入新的学号：";cin>>_id;
319                         p->id = _id;
320                     }
321                     break;
322                 case 2: 
323                     {
324                         cout<<"请输入新的年龄：";cin>>_age;
325                         p->age = _age;
326                     }
327                     break;
328                 case 3: 
329                     {
330                         cout<<"请按指示修改课程成绩..."<<endl;
331                         cout<<"是否需要修改第一门课程成绩？（需要输入【1】不需要输入【0】）"<<endl;
332                         cin >> course;
333                         if(course == 1)
334                         {
335                             cout<<"请输入修改后的第一门课的成绩："; cin >> p->score[0];
336                         }
337                         course = 0;
338                         
339                         cout<<"是否需要修改第二门课程成绩？（需要输入【1】不需要输入【0】）"<<endl;
340                         cin >> course;
341                         if(course == 1)
342                         {
343                             cout<<"请输入修改后的第二门课的成绩："; cin >> p->score[1];
344                         }
345                         course = 0;
346                         
347                         cout<<"是否需要修改第三门课程成绩？（需要输入【1】不需要输入【0】）"<<endl;
348                         cin >> course;
349                         if(course == 1)
350                         {
351                             cout<<"请输入修改后的第三门课的成绩："; cin >> p->score[2];
352                         }
353                         course = 0;
354                         
355                         p->total = p->score[0]+p->score[1]+p->score[2];
356                         p->average = p->total/3;
357                         
358                         cout<<"修改后的信息如下： "<<endl;
359                         cout<<"姓名:"<<p->name<<"  ";
360                         cout<<"年龄:"<<p->age<<"  ";
361                         cout<<"学号:"<<p->id<<"  ";
362                         cout<<"三门课程成绩: "<<p->score[0]<<" "<<p->score[1]<<" "<<p->score[2]<<"  ";
363                         cout<<"总分:"<<p->total<<"  ";
364                         cout<<"平均分:"<<p->average<<endl;    
365                     }
366                     break;
367                 default:  cout<<"输入有误..."<<endl;
368             }
369         }
370         p = p->next;
371     }
372     if(flag == 0)
373         cout<<"当前记录中没有次学生..."<<endl;
374 }
375 
376 /*排序我均采用冒泡排序法，均是从小到大排序*/
377 
378 
379 //按照科目一排序
380 void studentMessage::sortByLesson1(void) 
381 {
382     student *p = first->next;
383     while(p->next != null)
384     {
385         student *q = p->next;
386         while(q != null)
387         {
388             if(p->score[0] > q->score[0])
389             {
390                 p->swap(q);
391             }
392             q = q->next;
393         }
394         p = p->next;
395     }
396 }
397 
398 //按照科目二排序
399 void studentMessage::sortByLesson2(void)
400 {
401     student *p = first->next;
402     while(p->next != null)
403     {
404         student *q = p->next;
405         while(q != null)
406         {
407             if(p->score[1] > q->score[1])
408             {
409                 p->swap(q);
410             }
411             q = q->next;
412         }
413         p = p->next;
414     }
415 }
416 
417 //按照科目三排序
418 void studentMessage::sortByLesson3(void)
419 {
420     student *p = first->next;
421     while(p->next != null)
422     {
423         student *q = p->next;
424         while(q != null)
425         {
426             if(p->score[2] > q->score[2])
427             {
428                 p->swap(q);
429             }
430             q = q->next;
431         }
432         p = p->next;
433     }
434 }
435 
436 //按照总成绩排序
437 void studentMessage::sortByTotal(void)
438 {
439     student *p = first->next;
440     while(p->next != null)
441     {
442         student *q = p->next;
443         while(q != null)
444         {
445             if(p->total > q->total)
446             {
447                 p->swap(q);
448             }
449             q = q->next;
450         }
451         p = p->next;
452     }
453 }
454 
455 void studentMessage::clear(void)
456 {
457     student *p = first->next;
458     while(p != null)
459     {
460         first->next = p->next;
461         p->next = null;
462         delete p;
463         p = first->next;
464     }
465 }
466 
467 
468 
469 int main()
470 {
471     studentMessage stulist;
472     int ch;
473     while(ch = stulist.menu())
474     {
475         switch(ch)
476         {
477             case 1: stulist.Display(); break;
478             case 2: stulist.Insret(); break;
479             case 3: stulist.Search(); break;
480             case 4: stulist.Change(); break;
481             case 5: stulist.Delete(); break;
482             case 6: stulist.clear(); break;
483             default: cout<<"请按要求输入..."<<endl;
484         }
485     }
486     return 0;
487 }