Operatii cu numere mari

#include <iostream>

using namespace std;

int a[10000], b[10000], c[10000], na, nb, nc;

void Memoreaza(char s[], int v[], int &n)
{
    int i;
    n = 0;
    for (i = 0; s[i] != 0; i++)
        v[++n] = s[i] - '0';
    // inversez numarul mare
    for (i = 1; i <= n / 2; i++)
        swap(v[i], v[n-i+1]);
}

void Afisare(int v[], int n)
{
    for (int i = n; i >= 1; i--)
        cout << v[i];
    cout << "\n";
}

void Aduna(int a[], int na, int b[], int nb, int c[], int &nc)
{
    int i, t, x;
    if (na < nb)
        for (i = na + 1; i <= nb; i++)
            a[i] = 0;
    if (nb < na)
        for (i = nb + 1; i <= na; i++)
            b[i] = 0;
    nc = max(na, nb);
    t = 0;
    for (i = 1; i <= nc; i++)
    {
        x = a[i] + b[i] + t;
        if (x < 10)
        {
            c[i] = x;
            t = 0;
        }
        else
        {
            c[i] = x - 10;
            t = 1;
        }
    }
    if (t == 1)
        c[++nc] = 1;
}

//a = a * x
void Produs(int a[], int &na, int x)
{
    int t, i, w;
    t = 0;
    for (i = 1; i <= na; i++)
    {
        w = a[i] * x + t;
        a[i] = w % 10;
        t = w / 10;
    }
    while (t > 0)
    {
        a[++na] = t % 10;
        t /= 10;
    }
}

int Impartire(int a[], int na, int x, int b[], int &nb)
{
    int i, q, cobor;
    cobor = 0;
    nb = na;
    for (i = na; i >= 1; i--)
    {
        cobor = cobor * 10 + a[i];
        q = cobor / x;
        b[i] = q;
        cobor -= (q * x);
    }
    while (b[nb] == 0) nb--;
    return cobor;
}

void Scadere(int a[], int na, int b[], int nb, int c[], int &nc)
{
    int i, t, x;
    if (na < nb)
        for (i = na + 1; i <= nb; i++)
            a[i] = 0;
    if (nb < na)
        for (i = nb + 1; i <= na; i++)
            b[i] = 0;
    nc = max(na, nb);
    t = 0;
    for (i = 1; i <= nc; i++)
    {
        x = a[i] - b[i] + t;
        if (x < 0)
        {
            t = -1;
            c[i] = x + 10;
        }
        else
        {
            t = 0;
            c[i] = x;
        }
    }
    while (c[nc] == 0) nc--;
}

int main()
{
    char s[200];
    cin >> s;
    Memoreaza(s, a, na);
    cin >> s;
    Memoreaza(s, b, nb);
    Scadere(a,na,b,nb,c,nc);
    Afisare(c,nc);
    /*Afisare(a, na);
    Afisare(b,nb);
    Aduna(a,na,b,nb,c,nc);
    Afisare(c,nc);

    Produs(a, na, 128);
    Afisare(a, na);

    Memoreaza("1",a,na);
    for (int i = 2; i <= 18; i++)
        Produs(a,na,i);
    Afisare(a, na);
    cout << Impartire(a,na,3001,b,nb) << "\n";
    Afisare(b, nb);
    */
    return 0;
}