创建矩阵类:添加时出错
我正在尝试使用 C++ 创建一个 Matrix 类。到目前为止,我已经完成了以下工作:
- 创建矩阵
- 删除矩阵
- 获取和设置矩阵内部的值
现在,我正在努力覆盖所有运算符(即 +、-、*、/)并返回矩阵。我在这方面遇到了很多问题,所以我想知道是否有人可以提供帮助?
而且我在将矩阵复制到新矩阵中时也遇到问题,因此任何有关该代码的帮助将不胜感激。
注意:我有 Python 背景,并且了解一点 C++。我决定,虽然用 Python 创建很多非常酷的游戏和 OOP 东西很棒而且很酷,但我应该学习 C++,以便在我长大后找到一份工作。
这是我的代码,我有一个包含原型和类定义的标头,然后是主标头。
matrix.h
#ifndef MATRIX_H
#define MATRIX_H
/*
// These are all of the error codes
// Upon changing errorcode, Matrix should reset to null/void
*/
#define ERROR_ROW_NP 1 // Row Number cannot be non-positive
#define ERROR_COLUMN_NP 2 // Column Number cannot be non-positive
#define ERROR_ROW_I 3 // Row Index Error
#define ERROR_COLUMN_I 4 // Column Index Error
#define ERROR_RC_MISMATCH 5 // # of Rows and Columns do not match
class Matrix {
int row;
int column;
int elements;
int *RC;
public:
int ERRORCODE;
Matrix (void); // DONE
Matrix (int, int); // DONE
~Matrix (void); // DONE
void Copy (Matrix);
int get_value (int, int); // DONE
void set_value (int, int, int); // DONE
int rc_match (Matrix); // DONE
Matrix operator+ (Matrix);
Matrix operator- (Matrix);
Matrix operator* (Matrix);
Matrix operator* (int);
Matrix operator/ (int);
};
#endif
matrix.cpp
#include "matrix.h"
Matrix::Matrix (void) {
ERRORCODE = 0;
row = 1;
column = 1;
elements = row * column;
RC = new int[elements];
for (int i=0; i< elements; i++) {
RC[i] = 0;
}
}
Matrix::Matrix (int r, int c) {
ERRORCODE = 0;
row = r;
column = c;
elements = row * column;
RC = new int[elements];
for (int i=0; i< elements; i++) {
RC[i] = 0;
}
}
Matrix::~Matrix (void) {
delete[] RC;
}
// Copy will copy all of the contents of the toCopy
// matrix into itself; also resets it's own rows/columns
void Matrix::Copy (Matrix toCopy) {
row = toCopy.row;
column = toCopy.column;
elements = toCopy.elements;
RC = new int[elements];
for (int i=0; i<elements; i++) {
RC[i] = toCopy.RC[i];
}
}
int Matrix::get_value (int r, int c) {
return RC[(column*r)+c];
}
void Matrix::set_value (int r, int c, int value) {
RC[(column*r)+c] = value;
}
int Matrix::rc_match (Matrix a) {
if (
(row == a.row)
&&
(column == a.column)
) {
return (1);
}
else {
return (0);
}
}
Matrix Matrix::operator+ (Matrix a) {
if (rc_match(a)) {
Matrix OUT(row, column);
int z;
for (int i=0; i < row; i++) {
for (int j=0; j < column; j++) {
z = OUT.get_value(i, j) + a.get_value(i, j);
OUT.set_value(i, j, z);
}
}
return OUT;
}
else {
Matrix OUT(1, 1);
OUT.ERRORCODE = ERROR_RC_MISMATCH;
return OUT;
}
}
main.cpp
#include <iostream>
#include "matrix.h"
int main(void) {
Matrix a(2, 2);
a.set_value(0, 0, 3);
a.set_value(0, 1, 2);
Matrix b(2, 2);
b.set_value(0, 0, 1);
b.set_value(0, 1, 1);
b.set_value(1, 0, 3);
b.set_value(1, 1, 3);
printf("%d %d\n", a.get_value(0, 0), a.get_value(0, 1));
printf("%d %d\n", a.get_value(1, 0), a.get_value(1, 1));
printf("\n");
printf("%d %d\n", b.get_value(0, 0), b.get_value(0, 1));
printf("%d %d\n", b.get_value(1, 0), b.get_value(1, 1));
char t[1];
printf("Press 'Enter' to continue...");
std::cin.getline(t, 1);
printf("\n");
Matrix c;
c.Copy(a+b);
printf("%d %d\n", c.get_value(0, 0), c.get_value(0, 1));
printf("%d %d\n", c.get_value(1, 0), c.get_value(1, 1));
printf("Press 'Enter' to continue...");
std::cin.getline(t, 1);
printf("\n");
return (0);
}
我在编译和运行时遇到的错误是这样的:
Debug assertion failed! ...
Expression: _BLOCK_TYPE_IS_VALID(pHead ->nBlockUse)
按“Enter”后弹出
另外,这是我第一次发帖,如果我做错了什么,请告诉我:]
EDIT2: 我让它工作了! 谢谢@templatetypedef!
这是我使用的附加代码: (我发现我的add函数也错了) matrix.cpp
Matrix::Matrix(const Matrix& toCopy) {
row = toCopy.row;
column = toCopy.column;
elements = toCopy.elements;
RC = new int[elements];
for (int i=0; i<elements; i++) {
RC[i] = toCopy.RC[i];
}
}
Matrix Matrix::operator+ (Matrix a) {
if (rc_match(a)) {
Matrix OUT(row, column);
int z;
for (int i=0; i < row; i++) {
for (int j=0; j < column; j++) {
z = get_value(i, j) + a.get_value(i, j);
OUT.set_value(i, j, z);
}
}
return OUT;
}
else {
Matrix OUT(1, 1);
OUT.ERRORCODE = ERROR_RC_MISMATCH;
return OUT;
}
}
所以现在我将研究赋值运算符
I am trying to create a Matrix class using c++. So far, I have the following accomplished:
- Creating the Matrix
- Deleting the Matrix
- Getting and setting values inside of the matrix
Right now, I am working on overriding all of the operators (ie., +, -, *, /) and returning matrices. I'm having a lot of issues on this, so I was wondering if anyone could help?
And I'm also having issues with copying the matrix into a new one, so any help with that code would be appreciated.
Note: I am coming from a Python background, and I know a bit of c++. I decided that while yes, creating a lot of really cool games and OOP stuff in Python is awesome and cool, I should learn c++ in order to be getting a job when I'm older.
Here's my code, I have a header containing the prototype and the class definitions, then the main one.
matrix.h
#ifndef MATRIX_H
#define MATRIX_H
/*
// These are all of the error codes
// Upon changing errorcode, Matrix should reset to null/void
*/
#define ERROR_ROW_NP 1 // Row Number cannot be non-positive
#define ERROR_COLUMN_NP 2 // Column Number cannot be non-positive
#define ERROR_ROW_I 3 // Row Index Error
#define ERROR_COLUMN_I 4 // Column Index Error
#define ERROR_RC_MISMATCH 5 // # of Rows and Columns do not match
class Matrix {
int row;
int column;
int elements;
int *RC;
public:
int ERRORCODE;
Matrix (void); // DONE
Matrix (int, int); // DONE
~Matrix (void); // DONE
void Copy (Matrix);
int get_value (int, int); // DONE
void set_value (int, int, int); // DONE
int rc_match (Matrix); // DONE
Matrix operator+ (Matrix);
Matrix operator- (Matrix);
Matrix operator* (Matrix);
Matrix operator* (int);
Matrix operator/ (int);
};
#endif
matrix.cpp
#include "matrix.h"
Matrix::Matrix (void) {
ERRORCODE = 0;
row = 1;
column = 1;
elements = row * column;
RC = new int[elements];
for (int i=0; i< elements; i++) {
RC[i] = 0;
}
}
Matrix::Matrix (int r, int c) {
ERRORCODE = 0;
row = r;
column = c;
elements = row * column;
RC = new int[elements];
for (int i=0; i< elements; i++) {
RC[i] = 0;
}
}
Matrix::~Matrix (void) {
delete[] RC;
}
// Copy will copy all of the contents of the toCopy
// matrix into itself; also resets it's own rows/columns
void Matrix::Copy (Matrix toCopy) {
row = toCopy.row;
column = toCopy.column;
elements = toCopy.elements;
RC = new int[elements];
for (int i=0; i<elements; i++) {
RC[i] = toCopy.RC[i];
}
}
int Matrix::get_value (int r, int c) {
return RC[(column*r)+c];
}
void Matrix::set_value (int r, int c, int value) {
RC[(column*r)+c] = value;
}
int Matrix::rc_match (Matrix a) {
if (
(row == a.row)
&&
(column == a.column)
) {
return (1);
}
else {
return (0);
}
}
Matrix Matrix::operator+ (Matrix a) {
if (rc_match(a)) {
Matrix OUT(row, column);
int z;
for (int i=0; i < row; i++) {
for (int j=0; j < column; j++) {
z = OUT.get_value(i, j) + a.get_value(i, j);
OUT.set_value(i, j, z);
}
}
return OUT;
}
else {
Matrix OUT(1, 1);
OUT.ERRORCODE = ERROR_RC_MISMATCH;
return OUT;
}
}
main.cpp
#include <iostream>
#include "matrix.h"
int main(void) {
Matrix a(2, 2);
a.set_value(0, 0, 3);
a.set_value(0, 1, 2);
Matrix b(2, 2);
b.set_value(0, 0, 1);
b.set_value(0, 1, 1);
b.set_value(1, 0, 3);
b.set_value(1, 1, 3);
printf("%d %d\n", a.get_value(0, 0), a.get_value(0, 1));
printf("%d %d\n", a.get_value(1, 0), a.get_value(1, 1));
printf("\n");
printf("%d %d\n", b.get_value(0, 0), b.get_value(0, 1));
printf("%d %d\n", b.get_value(1, 0), b.get_value(1, 1));
char t[1];
printf("Press 'Enter' to continue...");
std::cin.getline(t, 1);
printf("\n");
Matrix c;
c.Copy(a+b);
printf("%d %d\n", c.get_value(0, 0), c.get_value(0, 1));
printf("%d %d\n", c.get_value(1, 0), c.get_value(1, 1));
printf("Press 'Enter' to continue...");
std::cin.getline(t, 1);
printf("\n");
return (0);
}
The error I am getting upon compiling and running is this:
Debug assertion failed! ...
Expression: _BLOCK_TYPE_IS_VALID(pHead ->nBlockUse)
That pops up after hitting 'Enter'
Also, this is my first time posting, if I did anything wrong, let me know please :]
EDIT2:
I got it to work!
Thank you @templatetypedef!
Here's the additional code I used:
(I found out that my add function was wrong too)matrix.cpp
Matrix::Matrix(const Matrix& toCopy) {
row = toCopy.row;
column = toCopy.column;
elements = toCopy.elements;
RC = new int[elements];
for (int i=0; i<elements; i++) {
RC[i] = toCopy.RC[i];
}
}
Matrix Matrix::operator+ (Matrix a) {
if (rc_match(a)) {
Matrix OUT(row, column);
int z;
for (int i=0; i < row; i++) {
for (int j=0; j < column; j++) {
z = get_value(i, j) + a.get_value(i, j);
OUT.set_value(i, j, z);
}
}
return OUT;
}
else {
Matrix OUT(1, 1);
OUT.ERRORCODE = ERROR_RC_MISMATCH;
return OUT;
}
}
So for now I shall look into the assignment operator
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评论(2)
我认为这里的问题是您的 Matrix 类有析构函数,但没有复制构造函数或复制赋值运算符。这意味着在运算符 + 的代码中,当您返回矩阵时,您将获得矩阵的浅副本而不是深层副本。这意味着浅拷贝将共享一个指向与运算符 + 中本地声明的矩阵相同元素的指针。当这个局部变量超出范围时,它的析构函数将触发,回收该矩阵的内存。因此,返回的矩阵将具有指向已释放内存的指针,从而导致未定义的行为。
要解决此问题,请尝试为您的 Matrix 类实现复制构造函数和赋值运算符。作为一个无耻的自我插件,我曾经写过一个关于如何做到这一点的指南,这在这里可能有用。
希望这有帮助!
I believe that the problem here is that your
Matrix
class has a destructor, but not a copy constructor or copy assignment operator. This means that in your code foroperator +
, when you return a matrix, you'll get a shallow copy of the matrix rather than a deep copy. This means that the shallow copy will share a pointer to the same elements as the locally-declared matrix inoperator +
. When this local variable goes out of scope, its destructor will fire, reclaiming the memory for that matrix. Consequently, the returned matrix will have a pointer to deallocated memory, resulting in undefined behavior.To fix this, try implementing a copy constructor and assignment operator for your
Matrix
class. As a shameless self-plug, I once wrote a guide on how to do this, which might be useful here.Hope this helps!
@templatetypedef 和@Kerrek 已经确定了您的问题。
通过使用 std::vector 来保存矩阵元素而不是手动管理内存,可以轻松解决此问题。复制构造函数和赋值运算符将由编译器自动实现,就
std::vector
的复制构造函数和赋值运算符而言,您可以摆脱析构函数代码。作为奖励,您可以删除Copy
函数及其内存泄漏。@templatetypedef and @Kerrek have identified your problem.
It can be solved trivially by using
std::vector
to hold your matrix elements instead of manually managing memory. Copy constructor and assignment operator will be implemented automatically by the compiler, in terms ofstd::vector
's copy constructor and assignment operator, and you can get rid of your destructor code. As a bonus, you could then remove theCopy
function along with its memory leak.