Приведение типов

#include <iostream>
using namespace std;
class ts
{
private:
unsigned short val;
public:
    ts():val(0){}
ts& operator=(ts& a){val=a.val;return *this;} 
ts& operator=(int a)
{
    if(a<0)a=0;
    else if(a>9)a=9;
    val=a;
    return *this;
}
friend ostream& operator<<(ostream& os,ts& a)
{
    os<<a.val;
    return os;
}
};
int main(int argc, char *argv[])
{
    const int nmax=2;
    ts chislo[nmax];
    chislo[0]=10;
    chislo[1]=chislo[0];
    cout<<chislo[0]<<" "<<chislo[1];
    system("pause");
}

#include <iostream>
 
enum dig 
   {
      zero, one, two, three, four, five, six, seven, eight, nine
   };
  
dig digit;
 
int main()
{
    digit = one;
    std::cout << digit << std::endl;
}

std:;set<char>

#include <iostream>
 
enum dig 
   {
      zero, one, two, three, four, five, six, seven, eight, nine
   };
  
dig digit;
 
int main()
{
    digit = static_cast<dig> (9);
    std::cout << digit << std::endl;
}

    std::set< int > first; //[0..9]
    for (int i = 0; i <= 9; ++i)
        first.insert(i);
        
    std::set< int > second; //[20..30]
    for (int i = 20; i <= 30; ++i)
        second.insert(i);
        
    std::set< int > third; //[0..9] + [20..30]
    std::set_union
    (
        first.begin(), first.end(),
        second.begin(), second.end(),
        std::inserter< std::set< int > > (third, third.begin() )
    );
    
    int x = 3;
    
    if ( third.find(x) != third.end() ) //...

int main()
{
    typedef unsigned char   u8;
    typedef unsigned short u16;
    typedef unsigned int   u32;
 
    u16 a = 1000;
    u16 b = 2000;
    u32 r = 0;
 
    u8  * a_ptr = (u8*)&a;
    u8  * b_ptr = (u8*)&b;
    u16 * r_ptr = (u16*)(void*)&r;
 
    Karatsuba_multiply(a_ptr, b_ptr, r_ptr);
 
    cout << r;
}