给出完整的C++代码：对字符串"January, February, March, April, May, June, July, September"进行排序，并输出排序后的结果，要求输出结果为：May、July、June、April、March、January、February、September (1) 排序的规则为：先比较两个字符串的长度，长度短的字符串排在前面，如果长度相等，则比较字符串的值，按从小到大排序输出。 (2) 用字符串数组存放各字符串，并在定义数组时对其进行初始化 (3) 利用库函数qsort实现排序操作

以下是符合要求的C++代码：

#include <iostream>
#include <cstring>
#include <cstdlib>
using namespace std;

int cmp(const void* a, const void* b) {
    const char* str1 = *(const char**)a;
    const char* str2 = *(const char**)b;
    int len1 = strlen(str1);
    int len2 = strlen(str2);
    if (len1 != len2) {
        return len1 - len2;
    }
    return strcmp(str1, str2);
}

int main() {
    const char* months[] = {"January", "February", "March", "April", "May", "June", "July", "September"};
    int len = sizeof(months) / sizeof(months[0]);
    qsort(months, len, sizeof(const char*), cmp);
    for (int i = 0; i < len; i++) {
        cout << months[i] << " ";
    }
    cout << endl;
    return 0;
}

运行结果为：May July June April March January February September