c 结构体最后一个成员使用长度为0数组

变长数组，不用指针，可以只分配一次内存，释放一次内存，方便内存管理

demo.c

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

struct demo {
    char ch1;
    char ch2;
    char str[0];
};

struct demo1 {
    char ch1;
    char ch2;
};


int main() {
    printf("sizeof demo:%d
", sizeof(struct demo));
    printf("sizeof demo1:%d
", sizeof(struct demo1));

    struct demo* buff = malloc(sizeof(struct demo) + 10);
    memset(buff->str, '', 10);
    memcpy(buff->str, "hello", 5);

    printf("buff->str:%s
", buff->str);

    return 0;
}