将整数写入到文件

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include<stdio.h>
#include <unistd.h>
#include <string.h>#include <stdlib.h>
int main()
{int fd;int data=100;int data2=0;fd=open("./file1",O_RDWR);int n_write=write(fd,&data,sizeof(int));//write的第二个参数是地址，并不一定非得是指针，所以可用&获取地址，read同理lseek(fd,0,SEEK_SET);int n_read=read(fd,&data2,sizeof(int));printf("read %d, write %d,context %d\n",n_read, n_write,data2);close(fd);return 0;
}
//文件中的数据有可能乱码，但并不影响程序对他的判断

将结构体写入到文件

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include<stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
struct text
{int a;char c;
};
int main()
{int fd;struct text data={100,'a'};struct text data2;fd=open("./file1",O_RDWR);//"./file1"    is    wenjianlujingint n_write=write(fd,&data,sizeof(struct text));//write  return zijie de changdulseek(fd,0,SEEK_SET);int n_read=read(fd,&data2,sizeof(struct text));printf("read %d,context %c\n",data2.a,data2.c);close(fd);return 0;
}

写结构体数组到文件

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include<stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
struct text
{int a;char c;
};
int main()
{int fd;struct text data[2]={{100,'a'},{101,'b'}};struct text data2[2];fd=open("./file1",O_RDWR);//"./file1"    is    wenjianlujingint n_write=write(fd,&data,sizeof(struct text)*22);//write  return zijie de changdulseek(fd,0,SEEK_SET);int n_read=read(fd,&data2,sizeof(struct text)*2);printf("read1 %d,context1 %c\n",data2[0].a,data2[0].c);printf("read2 %d,context2 %c\n",data2[1].a,data2[1].c);close(fd);return 0;
}