单链表中如何删除指定元素？用c语言写出来

单链表删除指定元素的步骤如下：
1. 遍历链表，找到待删除节点的前一个节点
2. 将待删除节点从链表中断开
3. 释放待删除节点的内存空间

以下是C语言代码示例：

#include <stdio.h>
#include <stdlib.h>

//定义单链表结构体
typedef struct ListNode {
    int val;
    struct ListNode* next;
} ListNode;

//创建单链表函数
ListNode* createList(int arr[], int n) {
    ListNode* head = (ListNode*)malloc(sizeof(ListNode));
    head->val = -1; //头节点不存储元素
    head->next = NULL;
    ListNode* tail = head;
    for (int i = 0; i < n; i++) {
        ListNode* node = (ListNode*)malloc(sizeof(ListNode));
        node->val = arr[i];
        node->next = NULL;
        tail->next = node;
        tail = node;
    }
    return head;
}

//删除指定元素函数
void deleteNode(ListNode* head, int val) {
    ListNode* prev = head;
    while (prev->next != NULL && prev->next->val != val) {
        prev = prev->next;
    }
    if (prev->next == NULL) { //未找到指定元素
        return;
    }
    ListNode* toDelete = prev->next;
    prev->next = toDelete->next;
    free(toDelete);
}

//测试程序
int main() {
    int arr[] = {1, 2, 3, 4, 5};
    int n = sizeof(arr) / sizeof(int);
    ListNode* head = createList(arr, n);
    printf("原始链表：");
    ListNode* cur = head->next;
    while (cur != NULL) {
        printf("%d ", cur->val);
        cur = cur->next;
    }
    printf("\n");
    deleteNode(head, 3);
    printf("删除元素3后的链表：");
    cur = head->next;
    while (cur != NULL) {
        printf("%d ", cur->val);
        cur = cur->next;
    }
    printf("\n");
    return 0;
}