C语言 在链表中删除

Question

我写了以下代码:

#include<stdio.h>
struct student{
char name[25];
double gpa;
struct student *next;
};
struct student *list_head;
struct student *create_new_student(char nm[], double gpa) 
{
         struct student *st;
         printf("tcreating nodet");
         printf("nName=%s t Gpa= %.2fn", nm, gpa);
         st = (struct student*)malloc(sizeof (struct student ));
         strcpy(st->name, nm);
         st->gpa = gpa;
         st->next = NULL;
         return st;
}
void printstudent(struct student *st) 
{
         printf("nName %s,GPA %fn", st->name, st->gpa);
}
void insert_first_list(struct student *new_node) 
{
         printf("nInserting node: ");
         printstudent(new_node);
         new_node->next = list_head;
         list_head = new_node;
}
struct student *delete_first_node() 
{
         struct student *deleted_node;
         printf("nDeleting node: ");
         printstudent(deleted_node);
         list_head = list_head->next;
         return deleted_node;
}
void printlist(struct student *st)
{
         printf("nPrinting list: ");
         while(st != NULL) {
             printstudent(st);
             st = st->next;
         }
}
int main() 
{
         struct student *other;
         list_head = create_new_student("Adil", 3.1);
         other = create_new_student("Fatima", 3.8);
         insert_first_list(other);
         printlist(list_head);
         other = delete_first_node();
         printlist(list_head);
         return 0;
}

当我运行它时，没有错误或警告。然而，它停在删除部分。消息说程序已停止工作。

你能帮我找到问题吗?

Answer 1

在函数delete_first_node中，节点deleted_node未初始化，传递给函数printstudent试图访问其成员，导致未定义行为
函数应该是

struct student *delete_first_node(){
    struct student *deleted_node = list_head;
    printf("nDeleting node: ");
    if(deleted_node != NULL)
    {
        printstudent(deleted_node);
        list_head= list_head->next;
        free(deleted_node);
    }
    else
       printf("List is emtyn");
    return list_head;
}