c++ 数据结构这个错在哪了，动态存储？

Question

找了半天了，麻烦帮我看下。 ///////////头文件 #ifndef POSTMASTER_H_INCLUDED #define POSTMASTER_H_INCLUDED #include<iostream> #include <stdio.h> #include <tchar.h> using namespace std; class Matrix { int rows, columns; int **element; void init(int rows, int columns); public: Matrix(int rows, int columns,int x); ~Matrix(); friend ostream& operator<<(ostream& out, Matrix&); }; #endif // POSTMASTER_H_INCLUDED ////////////////////.cpp #include "wine.h" void Matrix::init(int rows, int columns) { element = new int*[rows]; this->rows = rows; this->columns = columns; for (int i = 0;i < columns;i++) { element[i] = new int[columns]; } } Matrix::Matrix(int rows, int columns, int x) { this->init(rows, columns); cout << "1"; for (int i = 0;i < rows;i++) for (int j = 0;j < columns;j++) { element[i][j]=x; ///这里貌似出错了？ } } Matrix::~Matrix() { for (int i = 0;i < rows;i++) { delete element[i]; //delete[] element[i]; ? } delete element; } ostream& operator<<(ostream& os, Matrix&a) { os<< "矩阵(" << a.rows << "," << a.columns << "):" << endl; for (int i = 0;i < a.rows;i++) { os<< endl; for (int j = 0;j < a.columns;j++) os << a.element[i][j]<<" "; } return os; } //////////////////main() #include "wine.h" #include "wine.cpp" #include<iostream> #include<cstdlib> using namespace std; int main() { int b[3][2] = { 1,2,3,4,5,6 }; Matrix a(3,2,4); cout << a; system("PAUSE"); return 0; }

Answer 1

错误的关键在这一行：

element[i][j] = x;

这种寻址的使用方式会尝试访问element(首地址)+i*sizeof(int*)+j*sizeof(int)。
最好还是乖乖地使用：

int* row = element[i];
row[j] = x;

比较稳妥一些，也不怕不同的编译器有不同的解释方法。

Answer 2

for (int i = 0;i < columns;i++)
改为
for (int i = 0;i < rows;i++)