当你需要一个正方形或二维网格时,可以采用类似于编译器处理多维数组(真正的数组,而不是指向数组的指针)的方式,存储一个正确索引的单个大数组。
以下是使用下面的Matrix类的示例:
struct Map {
private:
Matrix<MapCell> cells;
public:
void loadMap() {
Matrix<MapCell> cells (WIDTH, HEIGHT);
for (int i = 0; i < WIDTH; i++) {
for (int j = 0; j < HEIGHT; j++) {
}
}
swap(this->cells, cells);
}
};
矩阵类的变种很多,有许多方法可以为特定用途进行定制。以下是一个不到100行的示例,可满足80%或更多的需求:
#include <algorithm>
#include <memory>
#include <vector>
template<class T, class A=std::allocator<T> >
struct Matrix {
typedef T value_type;
typedef std::vector<value_type, A> Container;
Matrix() : _b(0) {}
Matrix(int a, int b, value_type const& initial=value_type())
: _b(0)
{
resize(a, b, initial);
}
Matrix(Matrix const& other)
: _data(other._data), _b(other._b)
{}
Matrix& operator=(Matrix copy) {
swap(*this, copy);
return *this;
}
bool empty() const { return _data.empty(); }
void clear() { _data.clear(); _b = 0; }
int dim_a() const { return _b ? _data.size() / _b : 0; }
int dim_b() const { return _b; }
value_type* operator[](int a) {
return &_data[a * _b];
}
value_type const* operator[](int a) const {
return &_data[a * _b];
}
void resize(int a, int b, value_type const& initial=value_type()) {
if (a == 0) {
b = 0;
}
_data.resize(a * b, initial);
_b = b;
}
friend void swap(Matrix& a, Matrix& b) {
using std::swap;
swap(a._data, b._data);
swap(a._b, b._b);
}
template<class Stream>
friend Stream& operator<<(Stream& s, Matrix const& value) {
s << "<Matrix at " << &value << " dimensions "
<< value.dim_a() << 'x' << value.dim_b();
if (!value.empty()) {
bool first = true;
typedef typename Container::const_iterator Iter;
Iter i = value._data.begin(), end = value._data.end();
while (i != end) {
s << (first ? " [[" : "], [");
first = false;
s << *i;
++i;
for (int b = value._b - 1; b; --b) {
s << ", " << *i;
++i;
}
}
s << "]]";
}
s << '>';
return s;
}
private:
Container _data;
int _b;
};
vector<vector<...> >
。 - cobbal