C++ string当作buffer来使用

cppstr.cpp

// 2017.2.17
#include <iostream>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>

struct yfs_dir_entry {
        uint32_t inode;			/* Inode number */
	uint16_t rec_len;		/* Directory entry length */
	uint8_t  name_len;		/* Name length, word-aligned */
	uint8_t  file_type;             /* T_DIR or T_FILE */
	char     name[255];             /* File name */
} __attribute__((packed));


int main(int argc, char *argv[])
{
        struct yfs_dir_entry data = {13, 0, 1, 2, {'.', '\0', '\0', '\0' }};
        struct yfs_dir_entry *de;
        char *cbuf = (char*)(&data);
        std::string buf(cbuf, sizeof(data));

        printf("buf: sizeof(data)=%d, length=%d\n", sizeof(data), buf.length());

        de = (struct yfs_dir_entry *)buf.c_str();

        printf("inode=%d, rec_len=%d, name_len=%d, file_type=%d, name=%s\n",
                        de->inode, de->rec_len, de->name_len, de->file_type,
                        de->name);

        return 0;
}