how to write a struct to a file directly?

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我是靠谱客的博主大方山水，这篇文章主要介绍how to write a struct to a file directly?，现在分享给大家，希望可以做个参考。

Using write and read system call. Following is an example:

blk.h:

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#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>

struct data{
    char s[20];
    int d1;
    char c;
};

#define BLK_SIZE 25

writeb.c:

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#include "blk.h"

int main(){
    struct data *d= malloc(BLK_SIZE);
    d->d1= 8;
    d->c= 'a';
    strcpy(d->s, "first try..");

    int fd= open("blk.dat", O_RDWR | O_CREAT | O_EXCL, S_IREAD | S_IWRITE);
    write(fd, d, BLK_SIZE);
    printf("writed!n");
    close(fd);
    return 0;
}

readb.c:

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include "blk.h"

int main(){
    int fd;
    struct data *d;
    fd= open("blk.dat", O_RDWR);
    read(fd, d, BLK_SIZE);
    printf("%d, %c, %sn", d->d1, d->c, d->s);
    close(fd);
    return 0;
}