A really basic question. About reading binary file.

[wizardinred]

How can I read a particular number of records from a binary file.
For example, there is a file, whose records are like:

John 23 8888888
Mike 19 7777777
Rose 20 9999999
.
.
.
.

According to the order, they are name, age and phonenumber. Of course, they are binary records. Now, there are thousands of records in it, I just want to read three people out, how can I do? I know this is a really basic question, please help me. Thanks so much!

[wizardinred]

Such a piece of cake, please help me.
So sorry for writing in English, because the computer I am using now only has English OS.

[whyglinux]

如果你不知道一个记录（如 John 23 8888888 就是一个记录）的具体结构的话，你无法实现你的想法。

一个记录可以用如下的结构体来表示：

struct Record {
char name[num]; // 你要事先知道 num 是多少。
int age; // 你要事先知道 age 的类型是否是 int 还是其它类型
long others; // 你要事先知道 others 的类型是什么，不一定是 long。
};

弄清楚记录的结构之后就好办了，就可以用文件操作函数一个记录一个记录地读出来了。

[ma100]

同意whyglinux(山青水秀)
读的时候 可以用
FILE *fp=fopen("path","r+b");
long n;//第n条record
struct Record record;
fseek(fp, n*sizeof(struct Record),SEEK_SET);
fread(&record,sizeof(struct Record),1,fp);
fclose(fp);

[wizardinred]

Thank you guys very much. Actually this is a question of my practical. The objective is just test whether we can understand C++ read binary file depending on bytes. Anyway, you guys have given me a really nice answer, thanks again.