一、写一个整形数到文件

//Test6.c
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include<stdio.h>
#include<string.h>
int main()
{int fd;int data1 = 100;int data2 = 0;fd = open("./file",O_RDWR|O_CREAT);int n_write = write(fd,&data1,sizeof(int));lseek(fd,0,SEEK_SET);  //使光标移到开头int n_read = read(fd,&data2,sizeof(int));printf("read %d \n",data2);close(fd);return 0;
}
~ 

输出结果:

二、写一个结构体到文件

Test7.c
//Test4.c
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include<stdio.h>
#include<string.h>
struct Test
{int a;char c;};int main()
{int fd;struct Test data1 = {100,'a'};struct Test data2;fd = open("./file",O_RDWR|O_CREAT|O_TRUNC,0600);int n_write = write(fd,&data1,sizeof(struct Test));lseek(fd,0,SEEK_SET);int n_read = read(fd,&data2,sizeof(struct Test));printf("read %d,%c \n",data2.a,data2.c);close(fd);return 0;
}
~

输出结果:

二、写一个结构体数组到文件

//Test8.c
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include<stdio.h>
#include<string.h>
struct Test
{int a;char *c;};int main()
{int fd;struct Test data1[2] = {{666,"I will be successful"},{888,"We can do it" }};struct Test data2[2];fd = open("./file",O_RDWR|O_CREAT|O_TRUNC,0600);int n_write = write(fd,&data1,sizeof(struct Test)*2);lseek(fd,0,SEEK_SET);int n_read = read(fd,&data2,sizeof(struct Test)*2);printf("read %d,%s\n",data2[0].a,data2[0].c);printf("read %d,%s\n",data2[1].a,data2[1].c);close(fd);return 0;
}
~     

输出结果: