[linux系统编程]写入文件里的一定是字符串吗

一、写一个整形数到文件二、写一个结构体到文件二、写一个结构体数组到文件

//Test6.c
#include 
#include 
#include 
#include 
#include
#include
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:

Test7.c
//Test4.c
#include 
#include 
#include 
#include 
#include
#include
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:

//Test8.c
#include 
#include 
#include 
#include 
#include
#include
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,%sn",data2[0].a,data2[0].c);
        printf("read %d,%sn",data2[1].a,data2[1].c);
        close(fd);
        return 0;
}
~     

输出结果: