Файловая система

#include <iostream>
#include <fstream>
#include <time.h>
#include <ctime>
#include <cstdio>
using namespace std;
void pryamo(char buff[16385], int n);
void obratno(char buff[16385], int n);
int main(int)
{
setlocale(LC_ALL, "rus");
int k,n;
char buff[16385];
cout<<"Выберете прямо(1) или обратно(2)?\n\a";
cin>>k;
cout<<"Выберете 128 байт(1), 4096 байт(2), 16384 байт(3):\n\a";
cin>>n;
switch(n)
{
case 1: n=128; break;
case 2: n=4096; break;
case 3: n=16384; break;
}
switch(k)
{
case 1: pryamo (buff,n); break;
case 2: obratno(buff,n); break;
}
system ("pause");
return 0;
}
void pryamo(char buff[16385], int n)
{
int a=0;
long b;
FILE * fin;
fin=fopen("D:\\out.txt", "rb");
fseek(fin,0,SEEK_END);
b=ftell(fin);
fseek(fin,0,SEEK_SET);
clock_t start;
double diff;
start=clock();
 
while (a<b)
{
fread (buff,n,1,fin);
a+=n;
}
diff=(std::clock()-start)/(double)CLOCKS_PER_SEC;
cout<<diff<<endl;
}
void obratno(char buff[16385], int n)
{
int a;
FILE * fin;
fin=fopen("D:\\out.txt", "rb");
fseek(fin,0,SEEK_END);
a=ftell(fin);
clock_t start;
double diff;
start=clock();
while (a>0)
{
fseek(fin,-n,SEEK_CUR);
fread (buff,n,1,fin);
fseek(fin,-n,SEEK_CUR);
a-=n;
}