除了两个矩阵对象外，我还得到了垃圾值。 [英] I m getting garbage value in addition of two matrix objects.

问题描述

#include<iostream.h>
#include<conio.h>
class matrix
{
	public:
	int a[3][3];
	void getdata()
	{
		for(int i=1;i<=3;i++)
		{
			for(int j=1;j<=3;j++)
			{
				cout<<"Enter numbers for ["<<i<<"]["<<j<<"]";
				cin>>a[i][j];
			}
		}
	}
	void putdata()
	{
		for(int i=1;i<=3;i++)
		{
			for(int j=1;j<=3;j++)
			{
				cout<<a[i][j];
			}
		cout<<endl;
		}
	}
	friend void add(matrix,matrix);
};
void add(matrix m1,matrix m2)
{     //  matrix temp;
	int a,i,j;
	for(i=1;i<=3;i++)
	{      a[3][3]=0;
		for(j=1;j<=3;j++)
		{
		    //	temp.a[i][j]=x.a[i][j]+y.a[i][j];
			cout<<m1.a[i][j]+m2.a[i][j];
		}
		cout<<endl;
	}
    //   return temp;
}
int main()
{
	clrscr();
	matrix m1,m2,m3;
	m1.getdata();
	m2.getdata();
	add(m1,m2);
	m3.putdata();
	getch();
	return 0;
}

我的尝试：



i尝试了所有选项，并尝试了大部分网站的答案。

What I have tried:

i have tried all the options and tried mostly all the website for the answer.

推荐答案

C / C ++数组索引基于零。你有一个数组 a [3] [3] 。因此允许的索引在0到2的范围内。



更改所有循环以使用这些索引：

With C/C++ array indexes are zero based. You have an array a[3][3]. So the allowed indexes are in the range from 0 to 2.

Change all your loops to use these indexes:

for (int i = 0; i < 3; i++)
{
    for (int j = 0; j < 3; j++)
    {
        /* ... */
    }
}

除了 Jochen 建议外，我觉得更好矩阵加法的公式将是

In additon to Jochen advice, I think a better formulation of matrix addition would be

matrix addMatrix(const matrix & m1, const matrix & m2)
{
  matrix r;
  for (int i=0; i<3; ++i)
   for(j=0; j<3; ++j)
    r.a[i][j] = m1.a[i][j] + m2.a[i][j];
  return r;
}

另一个选项是 + 运算符重载，请参阅运营商重载 - cppreference.com [ ^ ]。

Another option would be + operator overloading, see operator overloading - cppreference.com[^].

当你不明白你的代码在做什么或者为什么它做它做的，答案是调试器。

使用调试器来查看你的代码在做什么。只需设置断点并查看代码执行情况，调试器允许您逐行执行第1行并在执行时检查变量，这是一个令人难以置信的学习工具。



调试器 - 维基百科，免费的百科全书 [ ^ ]

掌握Visual Studio 2010中的调试 - 初学者指南 [ ^ ]

使用Visual Studio 2010进行基本调试 - YouTube [ ^ ]

调试器在这里向您展示您的代码正在做什么以及您的任务是与它应该做的比较。

调试器中没有魔法，它没有发现错误，它只是帮助你。当代码没有达到预期的效果时，你就会接近一个错误。

When you don't understand what your code is doing or why it does what it does, the answer is debugger.
Use the debugger to see what your code is doing. Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute, it is an incredible learning tool.

Debugger - Wikipedia, the free encyclopedia[^]
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]
Basic Debugging with Visual Studio 2010 - YouTube[^]
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to. When the code don't do what is expected, you are close to a bug.

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