Dynamically Typed Dynamic List Example

class DynamicType {
public:
    union {
        int integer;
        char* string;
    };
    enum {
        is_int,
        is_string
    } what_type;
};

class DynamicTypeList {
    DynamicType* data;
    DynamicType* data_begin;
    DynamicType* data_end;
    int len;
    int actual_len;
    void expand() {
        int oldlen = actual_len;
        actual_len *= 2;
        DynamicType* temp = new DynamicType[actual_len];
        DynamicType* temp_begin = temp;
        data = data_begin;
        for (int i = 0; i < oldlen; i++) {
            temp->what_type = data->what_type;
            if (temp->what_type == temp->is_int)
                temp->integer = data->integer;
            else if (temp->what_type == temp->is_string)
                temp->string = data->string;
            temp++;
            data++;
        }
        delete[] data_begin;
        data = temp;
        data_end = temp;
        data_begin = temp_begin;
    }
public:
    DynamicTypeList() {
        constructor(100);
    }
    DynamicTypeList(int actual_len) {
        constructor(actual_len);
    }
    void constructor(int actual_len) {
        len = 0;
        this->actual_len = actual_len;
        data = new DynamicType[actual_len];
    }
    ~DynamicTypeList() {
        delete[] data_begin;
    }
    void add(int i) {
        if (len == actual_len) expand();
        len++;
        data->what_type = data->is_int;
        data->integer = i;
        data_end = data;
        if (len == 1) data_begin = data;
        data++;
    }
    void add(char* sz) {
        if (len == actual_len) expand();
        len++;
        data->what_type = data->is_string;
        data->string = sz;
        data_end = data;
        if (len == 1) data_begin = data;
        data++;
    }
    DynamicType* begin() const {
        return data_begin;
    }
    DynamicType* end() const {
        return data_end + 1;
    }
};