我想删除特定位置的节点,但我一直得到分段错误11.向后双向链表分段故障打印
我在读取文件中的位置和值。
这里是我的代码:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct node {
float val;
struct node *prev;
struct node *next;
}node_t;
void printForward(node_t *head) {
node_t *current = head;
while (current != NULL) {
printf("%.2f\n", current->val);
current = current->next;
}
}
void printBackward(node_t *head) {
node_t *current = head;
while (current->next != NULL) {
current = current->next;
}
while (current != NULL) {
printf("%.2f\n", current->val);
current = current->prev;
}
}
void deleteAtPos(node_t **head, int pos) {
int i;
node_t *current = *head;
node_t *temp = NULL;
if (pos == 0) {
temp = (*head)->next;
free(*head);
(*head) = temp;
(*head)->prev = NULL;
return;
}
for (i = 0; i < (pos - 1); i++) {
if (current->next != NULL) {
current = current->next;
}
}
temp = current->next;
current->next = temp->next;
free(temp);
}
// Fix insert at position
void insertAtPos(node_t **head, int pos, float val) {
int i;
node_t *newNode = malloc(sizeof(node_t));
node_t *current = *head;
newNode->val = val;
if (pos == 0) {
newNode->next = (*head);
newNode->prev = NULL;
(*head)->prev = newNode;
(*head) = newNode;
return;
}
for (i = 0; i < pos; i++) {
if (current->next != NULL) {
current = current->next;
}
else {
printf("Node does not exist\n");
break;
}
}
current->prev->next = newNode;
newNode->prev = current->prev;
newNode->next = current;
current->prev = newNode;
}
void addEnd(node_t **head, float val) {
node_t *current = *head;
node_t *newNode = malloc(sizeof(node_t));
newNode->next = NULL;
newNode->val = val;
if (*head == NULL) {
*head = newNode;
newNode->prev = NULL;
return;
}
while (current->next != NULL) {
current = current->next;
}
current->next = newNode;
newNode->prev = current;
}
int main(int argc, char *argv[]) {
if (argc != 2) {
printf("Error");
}
node_t *head = NULL;
FILE *fp;
int i = 0, x;
float valLine1, valLine2, valLine3;
char buffer[200], *token, *del = ",";
float posVals[200], delPos[200];
fp = fopen(argv[1], "r");
fgets(buffer, sizeof(buffer), fp);
token = strtok(buffer, del);
while (token != NULL) {
valLine1 = atof(token);
addEnd(&head, valLine1);
token = strtok(NULL, del);
}
printForward(head);
printf("\n");
del = ":,";
fgets(buffer, sizeof(buffer), fp);
token = strtok(buffer, del);
while (token != NULL) {
valLine2 = atof(token);
posVals[i] = valLine2;
token = strtok(NULL, del);
i++;
}
for (x = 0; x < i; x += 2) {
insertAtPos(&head, posVals[x + 1], posVals[x]);
}
printForward(head);
fgets(buffer, sizeof(buffer), fp);
i = 0;
token = strtok(buffer, del);
while (token != NULL) {
valLine3 = atof(token);
delPos[i] = valLine3;
token = strtok(NULL, del);
i++;
}
printf("\n");
for (x = 0; x < i; x++) {
deleteAtPos(&head, delPos[x]);
}
printForward(head);
printf("\n");
printBackward(head);
fclose(fp);
}
麻烦的是我的deleteAtPos功能,但我想不出为什么。
这里是输出:
24.00
0.04
17.00
-200.10
34.60
0.00
Segmentation fault: 11
这里是文件的内容:
17,32.5,12,0,34.6,-200.1,17,0.04,24
1:2,4.1:5,-12:4
3,5,0
请帮帮忙!
谢谢
检查你最后一个节点的逻辑。你将把值放在Null,Current-> next = temp-> next。这是错的 –
是的,我也这么认为,我尝试了许多不同的方式,但我无法使它工作。我实际上试图向后打印列表,这就是不断给我一个seg故障。我是否需要在删除功能中使用prev做任何事情? – CheetahBongos
为什么你不需要在需要删除的节点之前停止你的循环?因为你必须。维护prev指针也可以复制下一个节点的内容,并删除该节点而不是特定的节点。 –