Templates

Classes can be templated, which means that you can write generic code and the compiler will generate a class with the types that your code uses. The parameters can be types, constant integer values, or variadic versions (zero or more parameters, as provided by the code using the class). For example:

    template <int N, typename T> class simple_array 
    { 
        T data[N]; 
    public: 
        const T* begin() const { return data; } 
        const T* end() const { return data + N; } 
        int size() const { return N; } 

        T& operator[](int idx)  
        { 
            if (idx < 0 || idx >= N) 
                throw range_error("Range 0 to " + to_string(N)); 
            return data[idx]; 
        }  
    };

Here is a very simple array class that defines the basic iterator functions and the indexing operator, so that you can call it like this:

    simple_array<4, int> four; 
    four[0] = 10; four[1] = 20; four[2] = 30; four[3] = 40; 
    for(int...