如何在c中的字符数组中间插入多个字符？

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

void insertChars(char* str, int insertPos, char* charsToInsert) {
    int originalLen = strlen(str);
    int insertLen = strlen(charsToInsert);
    int newLen = originalLen + insertLen;

    char newStr[newLen + 1]; // +1 for null terminator

    // Copy characters before insert position
    strncpy(newStr, str, insertPos);
    newStr[insertPos] = '\0';

    // Copy characters to insert
    strcat(newStr, charsToInsert);

    // Copy characters after insert position
    strcat(newStr, str + insertPos);

    // Assign new string to original string
    strcpy(str, newStr);
}

int main() {
    char str[20] = "Hello World";
    char charsToInsert[] = "123";

    insertChars(str, 5, charsToInsert);

    printf("%s\n", str); // Output: Hello123 World

    return 0;
}