// MyLibManSys.cpp : Defines the entry point for the console application. 
//  #include "stdafx.h" #include "iostream"  struct book{   int id;   char title[20];   char author[20];   double price;   char state[20];   int student_id;   char student_name[20];   struct book* next; };  struct student{   int id;   char name[20];   char sex[10];   char borrow_book[30];   struct student* next; }; void Print_Book(struct book *head_book); void Print_Student(struct student *head_student); struct book *Create_New_Book();/*創建新的圖書庫*/  struct student *Create_New_Student();/*創建新的學生庫*/ struct book *Insert_Book(struct book *head_book,struct book *new_book);/*增加圖書，逐個添加*/  //void Insert_Book(struct book *head_book,struct book *new_book);/*增加圖書，逐個添加*/ //函數的參數是一個指針時，不要在函數體內部改變指針所指的地址，那樣毫無作用，需要修改的只能是指針所指向的內容。即應把指針當作常量 struct student *Insert_Student(struct student *head_student,struct student *new_student);/*增加學生，逐個添加*/  struct book *Search_Book_ById(int id,struct book *head_book);  struct book *Search_Book_ByTitle(char *title,struct book *head_book);  struct book *Search_Book_ByPrice(double price_h,double price_l,struct book *head_book); //bool Delete_Book(int id,book* head_book); struct book* Delete_Book(int id,book* head_book); struct student *Search_Student(int id,struct student *head_student); struct student* Delete_Student(int id,student* head_student);  void Lent_Book(int id,int student_id,struct book *head_book,struct student *head_student); void Back_Book(int id,int student_id,struct book *head_book,struct student *head_student);  int main() {   struct book* head_book,*p_book;   struct student* head_student, *p_student;   int choice, f, id, student_id;   int m = 1;   char name[20],sex[10];   char title[20];   double price_h,price_l,price;   char author[20];   int size_book=sizeof(struct book);   int size_student=sizeof(struct student);   printf("/n歡迎您第一次進入圖書管理系統!/n/n");    printf("----->[向導]----->[新建圖書庫]/n/n");    printf("注意:當輸入圖書編號為0時,進入下一步./n/n");    head_book=Create_New_Book();    system("cls");   //Print_Book(head_book);   printf("/n歡迎您第一次進入圖書管理系統!/n/n");    printf("----->[向導]----->[新建會員庫]/n/n");    printf("注意:當輸入會員學號為0時,進入主菜單./n/n");   head_student=Create_New_Student();    system("cls");   //Print_Student(head_student);   do{     printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");      printf("/n");      printf("/t/t/t[1]:借書辦理/t");printf(" [6]:還書辦理/n");      printf("/n");      printf("/t/t/t[2]:查詢圖書/t");printf(" [7]:查詢學生/n");      printf("/t/t/t[3]:添加圖書/t");printf(" [8]:添加學生/n");      printf("/t/t/t[4]:刪除圖書/t");printf(" [9]:刪除學生/n");      printf("/t/t/t[5]:遍歷圖書/t");printf("[10]:遍歷學生/n/n");      printf("/t/t/t〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓〓/n/n");      printf("/t/t/t0:退出/n/n");      printf("請選擇<0~10>:");      scanf("%d",&choice);     switch(choice){     case 0:       system("cls");        printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");        printf("/n謝謝您的使用!/n/n");        break;     case 1:       system("cls");       printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");       printf("輸入借出圖書編號:/n");        scanf("%d",&id);       printf("輸入借入學生學號：/n");       scanf("%d",&student_id);       Lent_Book(id,student_id,head_book,head_student);       break;     case 2:       system("cls");        printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");        printf("1.按編號查詢/n/n");        printf("2.按名稱查詢/n/n");        printf("3.按價格區間查詢/n/n");        printf("0.返回主菜單/n/n");        printf("請選擇:");        scanf("%d",&f);        if(f==1){          printf("請輸入查詢圖書編號:");          scanf("%d",&id);          printf("相關信息如下:/n/n");          head_book=Search_Book_ById(id,head_book);          break;        }        else if(f==2){         getchar();         printf("請輸入查詢圖書名稱:");          gets(title);         printf("相關信息如下:/n/n");          head_book=Search_Book_ByTitle(title,head_book);          break;        }        else if(f==3){          printf("請輸入最高價格:");          scanf("%lf",&price_h);          printf("請輸入最低價格:");          scanf("%lf",&price_l);          printf("相關信息如下:/n/n");          head_book=Search_Book_ByPrice(price_h,price_l,head_book);          break;        }        else if(f==0){          break;        }        break;     case 3:       system("cls");        printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");        printf("請輸入圖書編號:");        scanf("%d",&id);        printf("請輸入圖書名稱:");        scanf("%s",title);        printf("請輸入作者名字:");        scanf("%s",author);        printf("請輸入單價:");        scanf("%lf",&price);        printf("/n");       struct book *ptr_b;       for(ptr_b=head_book;ptr_b;ptr_b=ptr_b->next)        {         if(ptr_b->id==id)          {            printf("此編號圖書已存在/n");            m=0;            break;          }        }        if(m){          p_book=(struct book *)malloc(size_book);          strcpy(p_book->title,title);          p_book->id=id;          p_book->price=price;          p_book->student_id=-1;          strcpy(p_book->author,author);          strcpy(p_book->state,"存在");           strcpy(p_book->student_name,"待定");        // head_book=Insert_Book(head_book,p_book);          Insert_Book(head_book,p_book);         printf("/n添加圖書成功!/n/n");        }        break;     case 4:       system("cls");        printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");        printf("輸入刪除圖書編號:/n");        scanf("%d",&id);        /*if(Delete_Book(id,head_book)){         printf("/n刪除圖書成功!/n/n");       }else{         printf("刪除失敗");       }*/       head_book = Delete_Book(id,head_book);       break;     case 5:        system("cls");        printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");        Print_Book(head_book);        break;     case 6:       system("cls");       printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");       printf("輸入歸還圖書編號:/n");        scanf("%d",&id);       printf("輸入歸還學生學號：/n");       scanf("%d",&student_id);       Back_Book(id,student_id,head_book,head_student);       break;     case 7:       system("cls");        printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");          printf("請輸入查詢學生學號:");        scanf("%d",&id);        printf("相關信息如下:/n/n");        head_student=Search_Student(id,head_student);        break;     case 8:       system("cls");        printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");        printf("請輸入學生編號:");        scanf("%d",&id);        printf("請輸入學生姓名:");        scanf("%s",name);        printf("請輸入學生性別:");        scanf("%s",sex);         printf("/n");       struct student *ptr_s;       for(ptr_s=head_student;ptr_s;ptr_s=ptr_s->next)        {         if(ptr_s->id==id)          {            printf("此學號學生已存在/n");            m=0;            break;          }        }        if(m){          p_student=(struct student *)malloc(size_student);           p_student->id=id;           strcpy(p_student->name,name);          strcpy(p_student->sex,sex);           strcpy(p_student->borrow_book,"無");          head_student=Insert_Student(head_student,p_student);          printf("/n添加學生成功!/n/n");        }        break;     case 9:       system("cls");        printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");        printf("輸入刪除學生學號:/n");        scanf("%d",&id);        head_student = Delete_Student(id,head_student);       break;     case 10:       system("cls");        printf("/n/t/t/t〓〓〓〓〓圖書管理系統〓〓〓〓〓/n/n");        Print_Student(head_student);     }   }while(choice!=0);   return 0; }  struct book *Create_New_Book(){   struct book *head_book,*p_book;    int id, tag;    double price;    char title[20],author[20];    int size_book=sizeof(struct book);        head_book=NULL;    printf("請輸入圖書編號:");    scanf("%d",&id);    printf("請輸入圖書名稱:");    scanf("%s",title);    printf("請輸入作者名字:");    scanf("%s",author);    printf("請輸入單價:");    scanf("%lf",&price);    printf("/n");    while(true){      p_book=(struct book *)malloc(size_book);      strcpy(p_book->title,title);      p_book->id=id;      p_book->price=price;      p_book->student_id=-1;      strcpy(p_book->author,author);      strcpy(p_book->state,"存在");       strcpy(p_book->student_name,"待定");      head_book=Insert_Book(head_book,p_book);     printf("是否繼續？繼續輸入1，退出按任意鍵/n");     scanf("%d",&tag);     if(tag!=1){       break;     }     printf("請輸入圖書編號:");      scanf("%d",&id);      printf("請輸入圖書名稱:");      scanf("%s",title);      printf("請輸入作者名字:");      scanf("%s",author);      printf("請輸入單價:");      scanf("%lf",&price);      printf("/n");    }    return head_book; }  struct student *Create_New_Student(){   struct student *head_student,*p_student;    int id, tag;   char sex[10];   char name[20];    int size_student=sizeof(struct student);        head_student=NULL;    printf("請輸入學生編號:");    scanf("%d",&id);    printf("請輸入學生姓名:");    scanf("%s",name);    printf("請輸入學生性別:");    scanf("%s",sex);     printf("/n");    while(true){      p_student=(struct student *)malloc(size_student);       p_student->id=id;       strcpy(p_student->name,name);      strcpy(p_student->sex,sex);       strcpy(p_student->borrow_book,"無");      head_student=Insert_Student(head_student,p_student);      printf("是否繼續？繼續輸入1，退出按任意鍵/n");     scanf("%d",&tag);     if(tag!=1){       break;     }     printf("請輸入學生編號:");      scanf("%d",&id);      printf("請輸入學生姓名:");      scanf("%s",name);      printf("請輸入學生性別:");      scanf("%s",sex);       printf("/n");    }    return head_student; }  struct book *Insert_Book(struct book *head_book,struct book *new_book){   struct book *p,*q;    p=q=head_book;      if(head_book==NULL){  //單向鏈表為空的情況     head_book=new_book;     new_book->next = NULL;   }else{     while((new_book->id>p->id)&&(p->next!=NULL)){       q = p;       p = p->next;     }     if(new_book->id<=p->id){       new_book->next=p;       if(head_book==p)         head_book=new_book;       else         q->next = new_book;     }else{       p->next=new_book;       new_book->next=NULL;     }   }   return head_book; };  struct student *Insert_Student(struct student *head_student,struct student *new_student){   struct student *p,*q;    p=q=head_student;      if(head_student==NULL){ //單向鏈表為空的情況     head_student=new_student;     new_student->next = NULL;   }else{     while((new_student->id>p->id)&&(p->next!=NULL)){       q = p;       p = p->next;     }     if(new_student->id<=p->id){       new_student->next=p;       if(head_student==p)         head_student=new_student;       else         q->next = new_student;     }else{       p->next=new_student;       new_student->next=NULL;     }   }   return head_student; }  struct book *Search_Book_ById(int id,struct book *head_book){   struct book *ptr_book = head_book;    int flag=0;    while(ptr_book!=NULL)    {     if(ptr_book->id==id){       printf("圖書編號:%d/n",ptr_book->id);       printf("圖書名稱:%s/n",ptr_book->title);       printf("圖書單價:%.2lf/n",ptr_book->price);       printf("圖書作者:%s/n",ptr_book->author);       printf("存在狀態:%s/n",ptr_book->state);       printf("借書人姓名:%s/n",ptr_book->student_name);        printf("學號:%d/n",ptr_book->student_id);       printf("/n");       flag++;     }     if(flag>0)     {       break;     }     ptr_book = ptr_book->next;   }    if(flag==0){        printf("暫無此圖書信息!/n/n");    }    return head_book;  };  struct book *Search_Book_ByTitle(char *title,struct book *head_book){   struct book *ptr_book = head_book;    int flag=0;    while(ptr_book!=NULL)    {      if(strcmp(ptr_book->title,title)==0){        printf("圖書編號:%d/n",ptr_book->id);        printf("圖書名稱:%s/n",ptr_book->title);        printf("圖書單價:%.2lf/n",ptr_book->price);        printf("圖書作者:%s/n",ptr_book->author);        printf("存在狀態:%s/n",ptr_book->state);        printf("借書人姓名:%s/n",ptr_book->student_name);         printf("學號:%d/n",ptr_book->student_id);        printf("/n");        flag++;      }     if(flag>0)     {       break;     }     ptr_book = ptr_book->next;   }    if(flag==0){        printf("暫無此圖書信息!/n/n");    }    return head_book; };  struct book *Search_Book_ByPrice(double price_h,double price_l,struct book *head_book){   struct book *ptr_book = head_book;    int flag=0;    while(ptr_book!=NULL)    {      if(ptr_book->price>=price_l&&ptr_book->price<=price_h){        printf("圖書編號:%d/n",ptr_book->id);        printf("圖書名稱:%s/n",ptr_book->title);        printf("圖書單價:%.2lf/n",ptr_book->price);        printf("圖書作者:%s/n",ptr_book->author);        printf("存在狀態:%s/n",ptr_book->state);        printf("借書人姓名:%s/n",ptr_book->student_name);         printf("學號:%d/n",ptr_book->student_id);        printf("/n");        flag++;      }     ptr_book = ptr_book->next;   }    if(flag==0){        printf("暫無此圖書信息!/n/n");    }    return head_book; }  /*bool Delete_Book(int id,book* head_book){   bool flag=true;   struct book *p,*q;   p=q=head_book;   if(p->id==id&&p->next==NULL){     head_book=NULL;   }    while(p->id!=id&&p->next!=NULL){     q=p;     p=p->next;   }   if(p->id==id){     if(p==head_book){       head_book=p->next;     }else{       q->next=p->next;     }     free(p);   }else{     flag=false;     printf("找不到該書");   }   return flag; };*/  struct book* Delete_Book(int id,book* head_book){   bool flag=true;   struct book *p,*q;   p=q=head_book;    while(p->id!=id&&p->next!=NULL){     q=p;     p=p->next;   }   if(p->id==id){     if(p==head_book){       head_book=p->next;     }else{       q->next=p->next;     }      free(p);     printf("刪除成功！/n");   }else{     flag=false;     printf("找不到該書");   }   return head_book; };  struct student* Delete_Student(int id,student* head_student){   bool flag=true;   struct student *p,*q;   p=q=head_student;    while(p->id!=id&&p->next!=NULL){     q=p;     p=p->next;   }   if(p->id==id){     if(p==head_student){       head_student=p->next;     }else{       q->next=p->next;     }      free(p);     printf("刪除成功！/n");   }else{     flag=false;     printf("找不到該學生");   }   return head_student; };  struct student *Search_Student(int id,struct student *head_student){   struct student *ptr_student = head_student;    int flag=0;    while(ptr_student!=NULL)    {     if(ptr_student->id==id){       printf("學號:%d/n",ptr_student->id);       printf("姓名:%s/n",ptr_student->name);       printf("性別:%s/n",ptr_student->sex);       printf("借書:%s/n",ptr_student->borrow_book);        printf("/n");       flag++;     }     if(flag>0)     {       break;     }     ptr_student = ptr_student->next;   }    if(flag==0){        printf("暫無此學生信息!/n/n");    }    return head_student;  };  void Lent_Book(int id,int student_id,struct book *head_book,struct student *head_student){   struct book* p=head_book;   struct student* q=head_student;   if(p==NULL||q==NULL){     printf("書本或學生不存在/n");     return;   }   while(p!=NULL&&q!=NULL){     if(p->id!=id){       p=p->next;     }     if(q->id!=student_id){       q=q->next;     }     if(p->id==id&&q->id==student_id){       break;     }   }   if(p==NULL||q==NULL){     printf("書本或學生不存在/n");     return;   }else{     if(strcmp(p->state,"存在")!=0){       printf("書已借出!抱歉!");       return;     }else{       p->student_id=student_id;       strcpy(p->student_name,q->name);       strcpy(q->borrow_book,p->title);       strcpy(p->state,"已借出");       printf("已成功借出!/n");     }   } };  void Back_Book(int id,int student_id,struct book *head_book,struct student *head_student){   struct book* p=head_book;   struct student* q=head_student;   if(p==NULL||q==NULL){     printf("書本或學生不存在/n");     return;   }   while(p!=NULL&&q!=NULL){     if(p->id!=id){       p=p->next;     }     if(q->id!=student_id){       q=q->next;     }     if(p->id==id&&q->id==student_id){       break;     }   }   if(p==NULL||q==NULL){     printf("書本或學生不存在/n");     return;   }else{     if(strcmp(p->state,"存在")==0){       printf("書未借出!抱歉!");       return;     }else{       p->student_id=-1;       strcpy(p->student_name,"待定");       strcpy(q->borrow_book,"無");       strcpy(p->state,"存在");       printf("已成功歸還!/n");     }   } };  void Print_Book(struct book *head_book){   struct book* p=head_book;    if(p==NULL){      printf("/n無記錄/n/n");      return;    }    printf("/n圖書編號/t圖書名稱/t圖書單價/t圖書作者/n/n");    while (p!=NULL)   {     printf("%d/t/t%s/t/t%.2lf/t/t%s/n/n",p->id,p->title,p->price,p->author);     p = p->next;   } }  void Print_Student(struct student *head_student){   struct student* p=head_student;    if(p==NULL){      printf("/n無記錄/n/n");      return;    }    printf("/n學生姓名/t學生性別/t學生學號/n/n");    while (p!=NULL)   {     printf("%s/t/t%s/t/t%d/n",p->name,p->sex,p->id);     p = p->next;   } }