10_84.cpp

a programme set to teach you how to use c

#include<iostream.h>
#include<iomanip.h>
class matrix
{  //定义矩阵类
	short rows,cols;  //矩阵的行、列
	double *elems;  //存放矩阵中各元素，按行存放
public:
	matrix(){}
	matrix(short r,short c);
	double operator ()(short r,short c);
	  //重载运算符"()"，用来返回元素值
	void setelem(short r,short c,double v);
	  //给元素赋值
	friend matrix operator +(matrix p,matrix q);
	  //重载"+"，实现矩阵相加
	friend matrix operator -(matrix p,matrix q);
	friend matrix operator *(matrix p,matrix q);
	void print();
};
matrix::matrix(short r,short c)
{  
	rows=r; 
	cols=c;
	elems=new double[r*c];
}

double matrix::operator()(short r,short c)
{
	return (r>=1 && r<=rows && c>=1 && c<=cols)?
		elems[(r-1)*cols+(c-1)]:0.0;
}
void matrix::setelem(short r,short c,double v)
{
	if(r>=1 && r<=rows && c>=1 && c<=cols)
		elems[(r-1)*cols+(c-1)]=v;
	//在内存中是按照行顺序存放矩阵元素的，所以应对行、列进行换算，
	//算出在elems中的下标
}
matrix operator +(matrix p,matrix q)
{
	matrix m(p.rows,p.cols);
	if(p.rows!=q.rows || p.cols!=q.cols)
		return m;
	for(int r=1;r<=p.rows;r++)
		for(int c=1;c<=p.cols;++c)
			m.setelem(r,c,p(r,c)+q(r,c));
	return m;
}
matrix operator -(matrix p,matrix q)
{
	matrix m(p.rows,p.cols);
	if(p.rows!=q.rows || p.cols!=q.cols)
		return m;
	for(int r=1;r<=p.rows;r++)
		for(int c=1;c<=p.cols;c++)
			m.setelem(r,c,p(r,c)-q(r,c));
	return m;
}
matrix operator *(matrix p,matrix q)
{
	matrix m(p.rows,q.cols);
	if(p.cols!=q.rows)
		return m;
	for(int r=1;r<=p.rows;r++)
		for(int c=1;c<=q.cols;c++)
		{
			m.setelem(r,c,0.0);
			for(int i=1;i<=p.cols;i++)
				m.setelem(r,c,m(r,c)+p(r,i)*q(i,c));
		}
	return m;
}
void matrix::print()
{
	for(int r=1;r<=rows;r++)
	{
		for(int c=1;c<=cols;c++)
			cout<<setw(7)<<(*this)(r,c);
    //注意：this指针的用法，此句只能写成(*this)(r,c)形式，其它形式错误
	//使用*this标识被该重载函数成员正在操作的对象
		cout<<endl;
	}
}
void main()
{
	matrix a(2,3),b(2,3),c(3,2),d(2,3),e(2,2);
	a.setelem(1,1,-1.1);
	a.setelem(1,2,2.2);
	a.setelem(1,3,-3.3);
	a.setelem(2,1,4.4);
	a.setelem(2,2,-5.5);
	a.setelem(2,3,6.6);
	b.setelem(1,1,-1.2);
	b.setelem(1,2,2.3);
	b.setelem(1,3,-3.4);
	b.setelem(2,1,4.5);
	b.setelem(2,2,-5.6);
	b.setelem(2,3,6.7);
	c.setelem(1,1,-1.8);
	c.setelem(1,2,4.9);
	c.setelem(2,1,-2.1);
	c.setelem(2,2,5.2);
	c.setelem(3,1,-3.3);
	c.setelem(3,2,6.4);
	cout<<"A矩阵："<<endl;	a.print();
	cout<<"B矩阵："<<endl;  b.print();
	cout<<"C矩阵："<<endl;  c.print();
	d=a+b;
	cout<<"A+B矩阵："<<endl; d.print();
	d=a-b;
	cout<<"A-B矩阵："<<endl; d.print();
	e=a*c;
	cout<<"A*C矩阵："<<endl; e.print();
}