Convertire ZECIMAL,BINAR,OCTAL,HEXA

#include <iostream>
#include <string.h>
#include <stdio.h>
#include <math.h>

char binar[6];
char octal[6];


using namespace std;

void IntToBinar(int n)
{
    for(int i = 0; i <= 4; i++)
    {
        binar[i] = '0';
    }
    int j = 3;
    while(n>0)
    {
        if(n%2 == 0)
            binar[j] = '0';
        else
            binar[j] = '1';
        n = n / 2;
        j--;
    }
    for(int i = 0; i <= 3; i++)
    {
        cout<<binar[i];
    }
}

int BinarToInt()
{
   int numar = 0;
   int i = strlen(binar)-1;
   int j = 0;
   while(i>=0)
   {
       if(binar[i] == '1')
       {
           numar += pow(2,j);
       }
       i--;
       j++;
   }
   return numar;
}

int IntToOcta(int n)
{
   int octa;
   if(n / 8 > 0)
   {
       octa = 1;
       octa *= 10;
       octa = octa + (n % 8);
       n = n/8;
   }
   else
   {
       octa = 0;
       octa += (n % 8);
       n = n/8;
   }
   return octa;
}

void IntToHex(int n)
{
     int rest = 0;
     while (n > 0) {
        rest = n % 16;
        if (rest > 9) {
            switch (rest) {
               case 10: cout << "A"; break;
               case 11: cout << "B"; break;
               case 12: cout << "C"; break;
               case 13: cout << "D"; break;
               case 14: cout << "E"; break;
               case 15: cout << "F"; break;
            }
        }
        else {
            cout << rest;
        }
        n = n / 16;
    }
}

int OctalToInt(int numaroctal)
{
    int numar = 0, i = 0;

    while(numaroctal != 0)
    {
        numar += (numaroctal%10) * pow(8,i);
        ++i;
        numaroctal/=10;
    }

    i = 1;

    return numar;
}

int hexadecimalToDecimal(char hex[])
{
    int lungime = strlen(hex);
    int baza = 1;

    int zecimal = 0;

    for (int i=lungime-1; i>=0; i--)
    {

        if (hex[i]>='0' && hex[i]<='9')
        {
            zecimal += (hex[i] - 48)*baza;

            baza = baza * 16;
        }

        else if (hex[i]>='A' && hex[i]<='F')
        {
            zecimal += (hex[i] - 55)*baza;
            baza = baza*16;
        }
    }

    return zecimal;
}


int main()
{
    int baza;
    cout<<"Introdu baza:\n1.Zecimal\n2.Binar\n3.Octal\n4.Hexa\n\n";
    cin>>baza;

    switch(baza)
    {
        case 1: //Conversie din zecimal
        {
            int numar;
            cout<<"Introdu numarul Zecimal";cin>>numar;

            cout<<"Conversie din Zecial:\n\n";
            cout<<"Binar ";IntToBinar(numar);cout<<"\n";
            cout<<"Octal "<<IntToOcta(numar)<<"\n";
            cout<<"Hexa ";IntToHex(numar);cout<< "\n"; break;
        }
        case 2: //Conversie din binar
        {
            cout<<"Introdu numarul Binar";cin>>binar;

            cout<<"Conversie din Binar:\n\n";
            int numar = BinarToInt();
            cout<<"Zecimal "<<numar;cout<<"\n";
            cout<<"Octal "<<IntToOcta(numar)<<"\n";
            cout<<"Hexa ";IntToHex(numar);cout<< "\n"; break;
        }
        case 3: //Conversie din octal
        {
            int numaroctal;
            cout<<"Introdu numarul Octal";cin>>numaroctal;

            cout<<"Conversie din Octal:\n\n";
            int numar = OctalToInt(numaroctal);
            cout<<"Zecimal "<<numar;cout<<"\n";
            cout<<"Binar ";IntToBinar(numar);cout<<"\n";
            cout<<"Hexa ";IntToHex(numar);cout<< "\n"; break;
        }
        case 4: //Conversie din HEXA
        {
            char numarhex[20];
            cout<<"Introdu numarul HEXA";cin>>numarhex;

            cout<<"Conversie din HEXA:\n\n";
            int numar = hexadecimalToDecimal(numarhex);
            cout<<"Zecimal "<<numar;cout<<"\n";
            cout<<"Binar ";IntToBinar(numar);cout<<"\n";
            cout<<"Octa "<<IntToOcta(numar);cout<< "\n"; break;
        }
    }


    return 0;
}