Add Array2D_v2.hpp

Array2D_v2.hpp

@@ -0,0 +1,92 @@
+#ifndef ARRAY2D_HPP
+#define ARRAY2D_HPP
+
+#include <iostream>
+#include <stdexcept>
+// 这里仅以int二维数组为例，扩展为类模板很容易
+// 相比第一个版本，增加了复制构造、复制赋值、移动构造和移动赋值
+
+class Array2D
+{
+    int **arr;    // 指针数组退化为二级指针
+    int row, col; // 二维数组的行和列
+public:
+    Array2D(int _row, int _col) : row{_row}, col{_col}
+    {
+        // 先申请行，再申请列
+        arr = new int *[row]; // 设置行 每个元素都是int *
+        for (int i{0}; i < row; ++i)
+            arr[i] = new int[col];
+    }
+    ~Array2D()
+    {
+        // 注意释放的次序！
+        for (int i{0}; i < row; ++i)
+            delete[] arr[i];
+        delete[] arr;
+    }
+    Array2D(const Array2D &arr2d) : row{arr2d.row}, col{arr2d.col}
+    {
+        arr = new int *[row];
+        for (int i{0}; i < row; ++i)
+        {
+            arr[i] = new int[col];
+            for (int j{0}; j < col; ++j)
+                arr[i][j] = arr2d.arr[i][j];
+        }
+    }
+    Array2D &operator=(const Array2D &arr2d)
+    {
+        if (this == &arr2d)
+            return *this; // 避免自赋值
+        std::cout << "Copy Assign\n";
+        this->~Array2D();
+        row = arr2d.row;
+        col = arr2d.col;
+        arr = new int *[row];
+        for (int i{0}; i < row; ++i)
+        {
+            arr[i] = new int[col];
+            for (int j{0}; j < col; ++j)
+                arr[i][j] = arr2d.arr[i][j];
+        }
+        return *this;
+    }
+    Array2D(Array2D &&arr2d) : row{arr2d.row}, col{arr2d.col}
+    {
+        std::cout << "Move Construct\n";
+        arr = arr2d.arr; // 直接复制指针本身
+        arr2d.col = arr2d.row = 0;
+        arr2d.arr = nullptr; // 被移动的对象指针可置空
+    }
+    Array2D &operator=(Array2D &&arr2d)
+    {
+        std::cout << "Move Assign\n";
+        if (this == &arr2d)
+            return *this;
+        this->~Array2D(); // 释放已有内存
+        row = arr2d.row, col = arr2d.col;
+        arr = arr2d.arr;
+        arr2d.col = arr2d.row = 0;
+        arr2d.arr = nullptr;
+        return *this;
+    }
+
+    void print()
+    {
+        for (int i{0}; i < row; ++i)
+        {
+            for (int j{0}; j < col; ++j)
+                std::cout << arr[i][j] << '\t';
+            std::cout << '\n';
+        }
+    }
+    int *operator[](int i) const // 重载[]，允许暴露内部数据
+    {
+        if (i < 0 || i >= row)
+            throw std::out_of_range{"数组行下标越界\n"};
+        return arr[i];
+    }
+};
+
+#endif