本题要求实现两个函数,一个将输入的学生成绩组织成单向链表;另一个将成绩低于某分数线的学生结点从链表中删除。
struct stud_node *createlist();
struct stud_node *deletelist( struct stud_node *head, int min_score );
函数createlist利用scanf从输入中获取学生的信息,将其组织成单向链表,并返回链表头指针。链表节点结构定义如下:
struct stud_node {
int num; /*学号*/
char name[20]; /*姓名*/
int score; /*成绩*/
struct stud_node *next; /*指向下个结点的指针*/
};
输入为若干个学生的信息(学号、姓名、成绩),当输入学号为0时结束。
函数deletelist从以head为头指针的链表中删除成绩低于min_score的学生,并返回结果链表的头指针。
struct stud_node *createlist()
{
struct stud_node *pMove=NULL,*head=NULL,*tail=NULL;
pMove=(struct stud_node*)malloc(sizeof(struct stud_node));
scanf("%d",&pMove->num);
while(pMove->num!=0)
{
scanf("%s %d",pMove->name,&pMove->score);
if(head==NULL){
head=pMove;
}
else{
tail->next=pMove;
}
tail=pMove;
pMove=(struct stud_node*)malloc(sizeof(struct stud_node));
}
return head;
}
struct stud_node *deletelist( struct stud_node *head, int min_score )
{
struct stud_node* p=head;
if(!head)
return NULL;
p=(struct stud_node*)malloc(sizeof(struct stud_node));
while(p->next)
{
if(p->scorestruct stud_node* temp=p;
p=temp->next;
free(temp);
}
else
{
p=p->next;
}
}
return head;
}
为什么我这个代码是错的QAQ,有没有好心的给个意见!
修改如下,供参考:
#include <stdio.h>
#include <stdlib.h>
struct stud_node {
int num; //学号
char name[20]; //姓名
int score; //成绩
struct stud_node* next; //指向下个结点的指针
};
struct stud_node* createlist()
{
struct stud_node* pMove = NULL, * head = NULL, * tail = NULL;
while (1) //while (pMove->num != 0)//修改
{
pMove = (struct stud_node*)malloc(sizeof(struct stud_node));
pMove->next = NULL; //修改
scanf("%d", &pMove->num);
if (pMove->num == 0) { //修改
free(pMove);
break; //修改
}
scanf("%s %d", pMove->name, &pMove->score);
if (head == NULL) {
head = pMove;
}
else {
tail->next = pMove;
}
tail = pMove;
//pMove = (struct stud_node*)malloc(sizeof(struct stud_node)); //修改
}
return head;
}
struct stud_node* deletelist(struct stud_node* head, int min_score)
{
struct stud_node* p = head, * pre = NULL; //修改
if (!head)
return NULL;
//p = (struct stud_node*)malloc(sizeof(struct stud_node)); //修改
while (p) //while (p->next)
{
if (p->score < min_score)
{
if (p == head) { //修改
head = p->next; //修改
free(p); //修改
p = head; //修改
}
else {
pre->next = p->next; //修改
free(p); //修改
p = pre; //修改
}
}
else{
pre = p; //修改
p = p->next;
}
}
return head;
}
void print(stud_node* L)
{
stud_node* p = L;
while (p) {
printf("%d %s %d\n", p->num, p->name, p->score);
p = p->next;
}
}
int main()
{
struct stud_node* L;
L = createlist();
L = deletelist(L, 100);
print(L);
return 0;
}
你输入的num值写入的是pMove节点,但while循环结束时,你又新建了pMove,那么整个输入的num值就被冲掉了。如果num值你初始化为0的话,循环就结束了,只能输入一个节点;如果num没有初始化,那么就是个随机值,你这循环可能成为死循环
所以不要scanf("%d",&pMove->num);单独定义一个num变量吧