c - 为什么下面的代码会出现段错误？

Question

#include <stdio.h>
#include <stdlib.h>
struct node{
    int data;
    struct node *next;
 };

void print (struct node* ptr)
{
    struct node* iter = ptr;
    while (iter!=NULL)
    {
    printf ("%d",iter->data);
    iter = iter -> next;
    }
}

void printWantedIndice (struct node*ptr,int indice)
{
    struct node*iter=ptr;
    int counter=1;
    while (counter<indice)
    {
        iter = iter -> next;
        counter++;
    }
    printf ("%d",iter->next->data);
}

int main ()
{
    struct node* head = (struct node*)malloc(sizeof(struct node));
    head -> data = 15;
    head -> next -> data = 44;
    head -> next -> next  = NULL;
    print(head);

}

我尝试编写链接列表，第一个“打印”函数用于打印每个索引，第二个函数“printWantedIndice”是用于打印所需索引的函数。它给出了段错误。我不明白为什么。你能帮忙吗？

Answer 1

下面一行是原因:

head->next->data = 44;

由于 head->next 未初始化，因此尝试访问它时会出现段错误。