Sito eratostenesa

#include <iostream>
#include <conio.h>
#include <fstream>
#include <windows.h>
#include <sys/time.h>
using namespace std;

void fileOut(string, bool*, long long);
void consoleOut(bool*, long long);
void p(char, short = 0, short = 0, bool = true);
void color(short=0);

int main()
{
    color();
    cout<<"Do jakiej liczby mam szukac liczb pierwszych?\n";
    long long a, mem;
    MEMORYSTATUSEX memory;
    memory.dwLength=sizeof(memory);
    GlobalMemoryStatusEx(&memory);
    mem=memory.ullAvailPhys;
    do{
        cin>>a;
        if(a>(mem - 100*1024*1024))
        {
            color(1);
            cout<<"Zostaw te 100MB wolnego RAMu...\nPodaj liczbe nie wieksza niz "<<mem -(100*1024*1024)<<"\n";
            color();
        }
    }while(a>(mem -100*1024*1024));
    cout<<"\nGdzie mam wypisac wynik?\n1 - w konsoli\n2 - do pliku *.txt\n3 - do pliku i w konsoli\n";
    int wybor;
    cin>>wybor;
    string name;
    if(wybor==2 || wybor==3)
    {
        cout<<"Podaj nazwe pliku (bez rozszerzenia).\n";
        color(1);
        cout<<"-->Uwaga! Jezeli plik o podanej nazwie juz istnieje zostanie nadpisany i stracisz dane!<--\n";
        color(0);
        cin>>name;
        name+=".txt";
        cout<<endl;
    }
    p('t', 6, 0, false);
    bool* tab=new bool[a];
    for(long long i=0;i<a;i++)
            tab[i]=true;
    p('t');
    p('l', 2, 0, false);
    for(long long i=2;i*i<a;i++)
    {
        if(!tab[i])
                  continue;
        for(long long j=2*i;j<a;j+=i)
                tab[j]=false;
    }
    p('l');
    switch(wybor)
    {
        case 1: p('p', 5, 4, false); consoleOut(tab, a); p('p'); break;
        case 2: p('p', 5, 0, false); fileOut(name, tab, a); p('p'); break;
        case 3:
        default: p('p', 5, 4, false); fileOut(name, tab, a); consoleOut(tab, a); p('p');
    }
    p('u', 6, 0, false);
    delete[] tab;
    cout<<"\nSkonczylem\nNacisnij dowolny klawisz aby zakonczyc dzialanie programu";
    getch();
    return 0;
}

void fileOut(string name, bool* tab, long long size)
{
    fstream file(name.c_str());
    file.open(name.c_str(), ios::out | ios::app);
    for(long long i=2;i<size;i++)
            if(tab[i])
                      file<<i<<"\n";
    file.close();
}

void consoleOut(bool* tab, long long size)
{
    for(long long i=2;i<size;i++)
            if(tab[i])
                       cout<<i<<"\t";
    cout<<endl;
}

void p(char a, short l1, short l2, bool x)
{
    string napis;
    switch(a)
    {
        case 'l':napis="Licze...\n";break;
        case 'p':napis="Pisze...\n";break;
        case 't':napis="Przygotowuje tablice...\n";break;
        case 'u':napis="Usuwam tablice...\n";break;
    }
    timeval czas;
    static double dTime1, dTime2;
    if(!x)
    {
        color(l1);
        cout<<napis;
        color(l2);
        gettimeofday(&czas, NULL);
        dTime1 = czas.tv_sec+(czas.tv_usec/1000000.0);
    }
    if(x)
    {
            color();
            cout<<"Zajelo mi to ";
            color(1);
            gettimeofday(&czas, NULL);
            dTime2 = czas.tv_sec+(czas.tv_usec/1000000.0);
            cout<<dTime2-dTime1<<" sekund[e/y]\n";
    }
}

void color(short color)
{
    HANDLE handle=GetStdHandle(STD_OUTPUT_HANDLE);
    switch(color)
    {
        case -6: SetConsoleTextAttribute(handle, FOREGROUND_RED | FOREGROUND_BLUE);break;
        case -5: SetConsoleTextAttribute(handle, FOREGROUND_GREEN | FOREGROUND_BLUE);break;
        case -4: SetConsoleTextAttribute(handle, FOREGROUND_RED | FOREGROUND_GREEN);break;
        case -3: SetConsoleTextAttribute(handle, FOREGROUND_BLUE);break;
        case -2: SetConsoleTextAttribute(handle, FOREGROUND_GREEN);break;
        case -1: SetConsoleTextAttribute(handle, FOREGROUND_RED);break;
        case 0: SetConsoleTextAttribute(handle, FOREGROUND_INTENSITY | FOREGROUND_RED | FOREGROUND_GREEN | FOREGROUND_BLUE);break;
        case 1: SetConsoleTextAttribute(handle, FOREGROUND_INTENSITY | FOREGROUND_RED);break;
        case 2: SetConsoleTextAttribute(handle, FOREGROUND_INTENSITY | FOREGROUND_GREEN);break;
        case 3: SetConsoleTextAttribute(handle, FOREGROUND_INTENSITY | FOREGROUND_BLUE);break;
        case 4: SetConsoleTextAttribute(handle, FOREGROUND_INTENSITY | FOREGROUND_RED | FOREGROUND_GREEN);break;
        case 5: SetConsoleTextAttribute(handle, FOREGROUND_INTENSITY | FOREGROUND_GREEN | FOREGROUND_BLUE);break;
        case 6: SetConsoleTextAttribute(handle, FOREGROUND_INTENSITY | FOREGROUND_RED | FOREGROUND_BLUE);break;
        default: SetConsoleTextAttribute(handle, FOREGROUND_RED | FOREGROUND_GREEN | FOREGROUND_BLUE);
    }
}