试编写C程序，建立相应字符串存储结构，从键盘接受字符输入建立块链串存储结构，并完成在指定位置插入某个子串，在指定位置删除指定长度子串的操作，并打印输出相应操作的结果。

在C语言中，我们可以创建一个简单的字符串链表结构来实现这个功能。首先，我们需要定义一个节点结构体，包含字符和指向下一个节点的指针：

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

// 定义链表节点结构
typedef struct Node {
    char data;
    struct Node* next;
} Node;

// 创建链表头结点
Node* createList() {
    return (Node*)malloc(sizeof(Node));
}

// 插入节点到链表
void insertNode(Node** head, char data, int pos) {
    Node* newNode = createList();
    newNode->data = data;
    newNode->next = *head;

    if (pos == 0) {
        *head = newNode;
    } else {
        Node* current = *head;
        for (int i = 0; i < pos - 1 && current != NULL; i++) {
            current = current->next;
        }
        if (current != NULL) {
            newNode->next = current->next;
            current->next = newNode;
        }
    }
}

// 删除指定位置的子串
void deleteSubstring(Node** head, int start, int length) {
    if (*head == NULL || start + length > strlen(*head->data)) {
        return;
    }

    Node* prev = NULL;
    Node* curr = *head;
    for (int i = 0; i < start; i++) {
        curr = curr->next;
    }

    // 如果start位置在链表开始，直接删除
    if (curr == *head) {
        *head = curr->next;
    } else {
        while (length > 0) {
            prev->next = curr->next;
            curr = curr->next;
            length--;
        }
    }
}

// 打印链表内容
void printList(Node* head) {
    while (head != NULL) {
        printf("%c", head->data);
        head = head->next;
    }
    printf("\n");
}

int main() {
    Node* head = createList();
    char input[100];
    int position, subLength;
    
    printf("Enter characters to build the string: ");
    fgets(input, sizeof(input), stdin); // 获取用户输入
    input[strcspn(input, "\n")] = '\0'; // 移除换行符

    // 将输入的字符插入到链表中
    for (char c : input) {
        insertNode(&head, c, 0);
    }

    // 询问用户操作
    printf("Enter operation:\n1. Insert at position\n2. Delete substring\nYour choice: ");
    scanf("%d", &position);

    if (position == 1) {
        printf("Enter character to insert and position: ");
        getchar(); // 清除前一个输入的回车
        scanf(" %c%d", &input[0], &position);
        insertNode(&head, input[0], position);
    } else if (position == 2) {
        printf("Enter start position and length of substring to delete: ");
        scanf(" %d%d", &start, &subLength);
        deleteSubstring(&head, start, subLength);
    }

    // 打印操作后的链表
    printf("After operation: \n");
    printList(head);

    return 0;
}