/ 【例11 10】建立一個學生成績信息（包括學號、姓名、成績）的單向鏈表，學生數據按學號由小到大順序排列，要求實現對成績信息的插入、修改、刪除和遍歷操作。 / / 用鏈表實現學生成績信息的管理 / include include include struct stud_node{ int num; ...

/【例11-10】建立一個學生成績信息（包括學號、姓名、成績）的單向鏈表，學生數據按學號由小到大順序排列，要求實現對成績信息的插入、修改、刪除和遍歷操作。/

/* 用鏈表實現學生成績信息的管理 */

include<stdio.h>

include<stdlib.h>

include<string.h>

struct stud_node{
int num;
char name[20];
int score;
struct stud_node next;
};
struct stud_node Create_Stu_Doc(); /* 新建鏈表 /
struct stud_node InsertDoc(struct stud_node * head, struct stud_node stud); / 插入 /
struct stud_node DeleteDoc(struct stud_node * head, int num); /* 刪除 /
void Print_Stu_Doc(struct stud_node head); /* 遍歷 */

struct stud_node * Find(struct stud_node * head, int num); /查找/
struct stud_node * Modify(struct stud_node * head, int num, int score); /修改成績/
struct stud_node * Max(struct stud_node * head); /求最高分數的學生記錄/
struct stud_node * Min(struct stud_node * head); /求最低分數的學生記錄/
double Ave(struct stud_node * head); /求平均分/
void Save(struct stud_node * head);
struct stud_node *Read();

typedef struct stud_node *LNode;
LNode head,p;

int main(void)
{
struct stud_node head=NULL, p;
int choice, num, score;
char name[20];
int size = sizeof(struct stud_node);

do{
printf("1:Create 2:Insert 3:Delete 4:Print 5:Modify 6:Find 7:Max 8:Save 9:Read 10:Min 0:Exit\n");
scanf("%d", &choice);
switch(choice){
case 1:
head = Create_Stu_Doc();
break;
case 2:
printf("Input num,name and score:\n");
scanf("%d%s%d", &num,name, &score);
p = (struct stud_node *) malloc(size);
p->num = num;
strcpy(p->name, name);
p->score = score;
head = InsertDoc(head, p);
break;
case 3:
printf("Input num:\n");
scanf("%d", &num);
head = DeleteDoc(head, num);
break;
case 4:
Print_Stu_Doc(head);
break;
case 5:
printf("Input num:\n");
scanf("%d", &num);
printf("Input score:\n");
scanf("%d", &score);
head=Modify(head,num,score);
break;
case 6:
printf("Input num:\n");
scanf("%d", &num);
p=Find(head,num);
if(p!=NULL)
printf("%d\t%s\t%d \n", p->num, p->name, p->score);
else
printf("Not Found %d\n",num);
break;
case 7:
p=Max(head);
if(p!=NULL)
printf("%d\t%s\t%d \n", p->num, p->name, p->score);
else
printf("Not Found\n");
break;
case 8:
Save(head);
break;
case 9:
head=Read();
break;
case 10:
p=Min(head);
if(p!=NULL)
printf("%d\t%s\t%d \n", p->num, p->name, p->score);
else
printf("Not Found\n");
break;
case 0:
break;
}
}while(choice != 0);

return 0;
}

/新建鏈表/
struct stud_node * Create_Stu_Doc()
{
struct stud_node * head,*p;
int num,score;
char name[20];
int size = sizeof(struct stud_node);

head = NULL;
printf("Input num,name and score:\n");
scanf("%d%s%d", &num,name, &score);
while(num != 0){    /* 學號0表示輸入結束，且學號0對應的姓名和成績都要輸入 */ 
   p = (struct stud_node *) malloc(size);
   p->num = num;
   strcpy(p->name, name);
   p->score = score;
   head = InsertDoc(head, p);    /* 調用插入函數 */
   scanf("%d%s%d", &num, name, &score);

}
return head;
}

/* 插入操作 /
struct stud_node InsertDoc(struct stud_node * head, struct stud_node stud)
{
struct stud_node ptr ,ptr1, ptr2;

ptr2 = head; 
ptr = stud;                 /* ptr指向待插入的新的學生記錄結點 */

if(head == NULL){ /* 原鏈表為空時的插入 */ 
    head = ptr;             /* 新插入結點成為頭結點 */
    head->next = NULL;
}
else{             /* 原鏈表不為空時的插入 */
    while((ptr->num > ptr2->num) && (ptr2->next != NULL)){
        ptr1 = ptr2;        /* ptr1, ptr2各後移一個結點 */
        ptr2 = ptr2->next;
    }
    if(ptr->num <= ptr2->num){  
        if(head == ptr2)  head = ptr;/* 新插入結點成為頭結點 */
        else ptr1->next = ptr;       /* 在ptr1與ptr2之間插入新結點 */
        ptr->next = ptr2;
    }
    else{                            /* 新插入結點成為尾結點 */
        ptr2->next = ptr;
        ptr->next = NULL; 
    } 
}
return head;

}

/* 刪除操作 /
struct stud_node DeleteDoc(struct stud_node * head, int num)
{
struct stud_node ptr1, ptr2;

if(head == NULL)  /*鏈表空 */
    return NULL;
else if(head->num == num){
    /* 要被刪除結點為表頭結點 */
    while(head != NULL && head->num == num){  
        ptr2 = head;
        head = head->next;
        free(ptr2);
    }
}
else{
    /* 要被刪除結點為非表頭結點  */
    ptr1 = head;
    ptr2 = head->next; /*從表頭的下一個結點搜索所有符合刪除要求的結點 */
    while(ptr2 != NULL){
        if(ptr2->num == num){   /* ptr2所指結點符合刪除要求 */
            ptr1->next = ptr2->next;
            free(ptr2); 
        }
        else 
            ptr1 = ptr2;       /* ptr1後移一個結點 */
        ptr2 = ptr1->next;    /* ptr2指向ptr1的後一個結點 */
    }
}

return head;

}

/遍歷操作/
void Print_Stu_Doc(struct stud_node * head)
{
struct stud_node * ptr;

if(head == NULL){
    printf("\nNo Records\n");
    return;
}
printf("\nThe Students' Records Are: \n");
printf("Num\tName\tScore\n");
for(ptr = head; ptr != NULL; ptr = ptr->next)
    printf("%d\t%s\t%d \n", ptr->num, ptr->name, ptr->score);

}

struct stud_node * Find(struct stud_node * head, int num) /查找/
{
struct stud_node *ptr;

if(head==NULL)
    return NULL;
else
{
    for(ptr=head;ptr!=NULL;ptr=ptr->next)/*for迴圈從head開始到NULL迴圈*/ 
        if(ptr->num==num)
            break;
            return ptr;
}

}

struct stud_node * Modify(struct stud_node * head, int num, int score)/修改通過查找學號修改成績/
{
struct stud_node *ptr;

if(head==NULL)
    return NULL;
else
{
    for(ptr=head;ptr!=NULL;ptr=ptr->next)
        if(ptr->num==num)
        {
            ptr->score=score;
            break;
        }
                
    return head;
}

}

struct stud_node * Max(struct stud_node * head)
{
struct stud_node maxp,ptr;

if(head==NULL)
    return NULL;
else
{
    maxp=head;
    for(ptr=head->next;ptr!=NULL;ptr=ptr->next)
        if(maxp->score<ptr->score)
            maxp=ptr;
    
    return maxp;
}

}
struct stud_node * Min(struct stud_node * head)
{
struct stud_node minp,ptr;

if(head==NULL)
    return NULL;
else
{
    minp=head;
    for(ptr=head->next;ptr!=NULL;ptr=ptr->next)
        if(minp->score>ptr->score)
            minp=ptr;
    
    return minp;
}

}

void Save(struct stud_node * head)
{
FILE fp;
if((fp=fopen("data.txt","w")) == NULL){ /打開文件（套用）*/
printf("File open error!\n");
exit(0);
}

struct stud_node * ptr;

if(head == NULL){
    return;
}

for(ptr = head; ptr->next != NULL; ptr = ptr->next)
    fprintf(fp,"%d %s %d\n", ptr->num, ptr->name, ptr->score);
fprintf(fp,"%d %s %d", ptr->num, ptr->name, ptr->score);/*輸出的最後沒有換行*/
      
if( fclose(fp) ){/*關閉文件（套用）*/
    printf( "Can not close the file!\n" );
    exit(0);
}

}

struct stud_node Read()
{
FILE fp;
if((fp=fopen("data.txt","r")) == NULL){
printf("File open error!\n");
exit(0);
}

struct stud_node * head,*tail,*p;
//int num,score;
//char  name[20];
int size = sizeof(struct stud_node);

head = tail=NULL;


while(!feof(fp)){   /* 讀到結束標誌結束 */ 
   p = (struct stud_node *) malloc(size);
   fscanf(fp,"%d%s%d", &p->num, p->name, &p->score);
   //head = InsertDoc(head, p);    /* 調用插入函數 */
   p->next = NULL;
    if(head == NULL) 
        head = p;
    else  
        tail->next = p;
    tail = p;

}

     if( fclose(fp) ){
    printf( "Can not close the file!\n" );
    exit(0);
}

return head;

}

學生信息鏈表，建立，插入，刪除，遍歷，查找，修改，最大（小）值，平均

include<stdio.h>

include<stdlib.h>

include<string.h>