分段错误核心转储 [C 语言，链表]

Question

我想显示我的列表，但是，我的print()函数似乎有问题。请帮帮我！多谢。我试图创建一个具有单个链表的学生管理系统，下面只有 2 个函数将数据输入列表并在插入或删除任何内容之前显示它。据我所知，当我想访问不允许的内存时，会发生分段错误，但它是如此普遍。我需要一些详细的解释和一些解决方案！

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define ID_LENGTH 5
#define NAME_LENGTH 51
typedef struct Student_t {
  char id[ID_LENGTH];
  char name[NAME_LENGTH];
  int grade;
  struct Student_t *next; 
} Student;
Student* head;
void input(){
  int n,i;
  Student* temp = (Student*) malloc(sizeof(Student*));
  printf("Enter the number of students: ");
  scanf("%d",&n);
  for(i=0;i<n;i++){
    printf("Enter the information of student no.%dn",i+1);
    printf(" -ID: "); scanf("%s",&temp->id);
    printf(" -Name: "); //getchar(); gets(temp->name); //
    scanf("%s",&temp->name);
    printf(" -Grade: "); scanf("%d",&temp->grade);
  }
}
void print(){
  Student* temp = (Student*) malloc(sizeof(Student*));
  temp = head;
  printf("ttThe Student Listnn");
  printf("%-10s%-40s%-10sn","ID","Name","Grade");
  while(temp->next != NULL){  
    printf("%-10s%-40s%-10dn",temp->id,temp->name,temp->grade);
    temp = temp->next;
  }
}
int main(){
  // head = NULL; //empty list
  input();  
  print();
}

Answer 1

在实现链接列表时，请始终使用笔和纸，并在开始编码之前正确写下每个步骤。编写创建列表、插入新节点、删除节点的每个步骤。不要忘记在创建新节点时将next指针分配给 NULL。大多数情况下，问题始终与next有关，因为列表的最后一个节点的next是用垃圾值而不是 NULL 分配的。

现在首先更正下面的语句。在这里你应该提供结构名称而不是指针：-

Student* temp = (Student*) malloc(sizeof(Student));
temp->next = NULL;//always do it
head = temp;// now head is pointing to the first node of the list

你下面的for循环是完全错误的。您不是在此处创建列表。您一直在使用同一个节点。

for(i=0;i<n;i++){
printf("Enter the information of student no.%dn",i+1);
printf(" -ID: "); scanf("%s",&temp->id);
printf(" -Name: "); //getchar(); gets(temp->name); //
scanf("%s",&temp->name);
printf(" -Grade: "); scanf("%d",&temp->grade);

}

更正如下：-

int i = 0;
while(1){       
printf("Enter the information of student no.%dn",i+1);
printf(" -ID: "); scanf("%s",&temp->id);
printf(" -Name: "); //getchar(); gets(temp->name); //
scanf("%s",&temp->name);
printf(" -Grade: "); scanf("%d",&temp->grade);
if( ++i < n ){// each time you have to create a new node
   temp->next = (Student*) malloc(sizeof(Student));
   temp = temp->next;
   temp->next = NULL;
}
else
   break;
}

更正您的print功能，如下所示：-

void print(){
  Student* temp = head;// here you no need to create a new node. Just create a node which will point to the head
  printf("ttThe Student Listnn");
  while(temp != NULL){  
    printf("%-10s%-40s%-10dn",temp->id,temp->name,temp->grade);
    temp = temp->next;
  }
}