#include <stdio.h>

typedef struct _user_info {
	int id;
	char name[20];
} user_info;

int main()
{
	user_info user;
	FILE *fp;

	user.id = 20;
	strncpy (user.name, "yangh", 5);
	user.name[5] = '\0';

	fp = fopen("data", "wb");
	fwrite (&user, sizeof(user_info), 1, fp);
	fclose (fp);

	return 1;
}