[英]Segmentation fault, pointer issue
#include <stdio.h>
#include <stdlib.h>
typedef struct lista_inteiros
{
int valor;
struct lista_inteiros *next;
}element_int;
void insere_inteiro(element_int **head, element_int **aux, int m);
void remove_inteiro(element_int **head, element_int **aux, int m);
int main()
{
int i = 0;
element_int *head, *aux;
head = NULL;
for(i = 0; i<6; i++)
{
insere_inteiro(&head, &aux, i);
}
aux = head;
while(aux)
{
printf("%d\n", aux->valor);
aux = aux->next;
}
aux = head;
i = 4;
remove_inteiro(&head, &aux, i);
aux = head;
while(aux)
{
printf("%d\n", aux->valor);
aux = aux->next;
}
return 0;
}
void insere_inteiro(element_int **head, element_int **aux, int m)
{
(*aux) = (element_int*)malloc(sizeof(element_int));
if((*aux) == NULL)
{
printf("Error\n");
exit(1);
}
(*aux)->valor = m;
(*aux)->next = (*head);
(*head) = (*aux);
}
void remove_inteiro(element_int **head, element_int **aux, int m)
{
element_int *del;
while((*aux) != NULL)
{
if((*head)->valor == m)
{
(*head) = (*head)->next;
free(aux);
(*aux) = (*head);
}
else if((*aux)->next->valor == m)
{
del = (*aux)->next;
(*aux)->next = del->next;
free(del);
}
(*aux) = (*aux)->next;
}
}
Baiscally, this prints: Baiscally,此打印:
5
4
3
2
1
0
Segmentation Fault
And i really cant figure out why. 我真的不知道为什么。 It is supposed to eliminate the number 4, and then print the numbers again. 应该消除数字4,然后再次打印数字。 So the desired output is: 因此,所需的输出为:
5
4
3
2
1
0
5
3
2
1
0
The function insere_inteiro
creates a new element and the function remove_inteiro
removes one. 函数insere_inteiro
创建一个新元素,而函数remove_inteiro
删除一个元素。
Each element of the list has a integer called valor
. 列表中的每个元素都有一个称为valor
的整数。
您可以在else if((*aux)->next->valor == m)
取消引用下一个值,而不检查是否存在
You dereference NULL, here's a fixed version: 您取消引用NULL,这是一个固定版本:
#include <stdio.h>
#include <stdlib.h>
typedef struct lista_inteiros
{
int valor;
struct lista_inteiros *next;
}element_int;
void insere_inteiro(element_int **head, element_int **aux, int m);
void remove_inteiro(element_int **head, element_int **aux, int m);
int main()
{
int i = 0;
element_int *head, *aux;
head = NULL;
for(i = 0; i<6; i++)
{
insere_inteiro(&head, &aux, i);
}
aux = head;
while(aux)
{
printf("%d\n", aux->valor);
aux = aux->next;
}
aux = head;
i = 4;
remove_inteiro(&head, &aux, i);
aux = head;
while(aux)
{
printf("%d\n", aux->valor);
aux = aux->next;
}
return 0;
}
void insere_inteiro(element_int **head, element_int **aux, int m)
{
(*aux) = (element_int*)malloc(sizeof(element_int));
if((*aux) == NULL)
{
printf("Error\n");
exit(1);
}
(*aux)->valor = m;
(*aux)->next = (*head);
(*head) = (*aux);
}
void remove_inteiro(element_int **head, element_int **aux, int m)
{
element_int *del;
while((*aux) != NULL)
{
if((*head)->valor == m)
{
(*head) = (*head)->next;
free(aux);
(*aux) = (*head);
}
/* CHANGED BELOW TO CHECK FOR NULL BEFORE DEREFERENCE */ / *更改为在引用后检查是否为空* /
else if(((*aux)->next != NULL) && ((*aux)->next->valor == m))
{
del = (*aux)->next;
(*aux)->next = del->next;
free(del);
}
(*aux) = (*aux)->next;
}
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.