自己编写的一个矩阵类,个人感觉从文件中读取矩阵和将矩阵写入文件这两个函数作用大些。
收获:1. 对类的static成员函数的作用有所了解。
2. 对文件的读写操作熟练了一些。clear,seekg等
3. 对异常处理的初级应用。
下面把代码贴出来吧
//Matrix.h
//矩阵类定义
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#ifndef MATRIX_H
#define MATRIX_H
#include <iostream>
#include <string>
//using namespace std; 一般头文件中使用完全限定域名字,而不是包含命名空间,防止重复包含头文件时造成的资源浪费
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class Matrix
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{
//从流中读入矩阵
friend std::istream& operator >> (std::istream& is, Matrix A);
//输出矩阵
friend std::ostream& operator << (std::ostream& os, const Matrix& A);
//将矩阵输出到名为str的文件中
friend void print_file(const Matrix&A,const char* str);
public:
//定义空矩阵
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Matrix()
{elems = NULL; row = 0; col = 0;};
//定义m*n零矩阵
Matrix(int m, int n);
//定义m*n矩阵,由a初始化
Matrix(int m, int n, double *a, int size = 0);
//复制构造函数
Matrix(const Matrix& B);
//从文件str中读取矩阵
Matrix(const char* str);
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~Matrix()
{delete[]elems; row = 0; col = 0; };
//重载算数操作符
Matrix& operator = (Matrix& B);
Matrix operator +(const Matrix&B)const;
Matrix operator -(const Matrix&B)const;
Matrix operator *(const Matrix&B)const;
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//返回矩阵第i行第j列元素
double& operator()(int i,int j)const;
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double get_row()const
{return row;};
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double get_col()const
{return col;};
//矩阵转置
Matrix& trans()const;
protected:
private:
double* elems;
int row, col;
};
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#endif
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//Matrix.cpp
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//函数实现
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#include "Matrix.h"
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#include <iostream>
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#include <fstream>
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#include <sstream>
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#include <string>
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#include <stdexcept>
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using namespace std;
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//重载下标操作符,返回A[i,j]
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double& Matrix::operator()(int i,int j)const
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{
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if(i<0 || i >= row || j < 0 || j >= col)
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throw out_of_range("The suffix is out of range");
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return elems[i*col+j];
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}
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//从输入流中读入矩阵
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istream& operator >>(istream& is, Matrix&A)
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{
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for(int i = 0; i != A.get_row(); ++i)
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for(int j = 0; j != A.get_col(); ++j)
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is >> A(i,j);
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return is;
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}
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//输出矩阵
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ostream& operator <<(ostream& os, const Matrix& A)
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{
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for(int i = 0; i != A.get_row(); ++i)
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{
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for(int j = 0; j != A.get_col(); ++j)
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os << A(i,j) << " ";
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cout <<endl;
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}
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cout << "------------------------" <<endl;
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return os;
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};
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//将矩阵A输出到文件str中
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void print_file(const Matrix&A,const char* str)
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{
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ofstream outfile("Matrix_out.txt",ios::app);
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if(!outfile)
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throw domain_error("Cannot open this file.");
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for(int i = 0; i != A.row; ++i)
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{
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for(int j = 0; j!= A.col; ++j)
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outfile << A(i,j);
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outfile << endl;
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}
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outfile << "----------------------"<<endl;
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outfile.clear();
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outfile.close();
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}
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//构造m*n零矩阵
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Matrix::Matrix(int m, int n):row(m),col(n)
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{
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if(m <1 || n <1)
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throw out_of_range("The row or column number should be larger than 0.");
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elems = new double[m*n];
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for(int i = 0; i != m*n; ++i)
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elems[i] = 0;
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}
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//构造m*n矩阵,从数组a中读入数据存储到矩阵中
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Matrix::Matrix(int m, int n,double* a, int size):row(m),col(n)
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{
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if(m <0 || n<0 || size < m*n)
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throw out_of_range("The suffix or size are out of range");
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elems = new double[m*n];
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for(int i = 0; i != m*n; ++i)
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elems[i] = a[i];
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};
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//从文件中读入矩阵
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Matrix::Matrix(const char* str)
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{
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//忘了刚开始的行列初始化,导致错误,寻找了半天。
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row = 0;
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col = 0;
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ifstream infile(str,ios::in);
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if(!infile)
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{
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throw domain_error("Cannot find this file.");
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}
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char ch = ' ';
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//计算列数
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while(infile.get(ch) && ch != '\n')
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{
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if(ch == ' ') ++col;
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}
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++col;
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//计算行数
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infile.clear(); //在这里这个语句不必要
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infile.seekg(0,ios::beg);//千万不能忘了重定位到文件头
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while(infile.get(ch))
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{
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if(ch == '\n') ++row;
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}
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++row;
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infile.clear();//已经读到文件尾时想重新定位到文件头必须有这条语句
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infile.seekg(0,ios::beg);
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elems = new double[row*col];
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int i = 0;
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while(i != row*col)
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infile >> elems[i++];
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infile.clear();
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infile.close();
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}
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//矩阵复制构造函数
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Matrix::Matrix(const Matrix& B):row(B.row),col(B.col)
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{
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if((row != B.row) || (col != B.col))
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throw invalid_argument("The Matrix should be matched.");
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elems = new double[row*col];
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for(int i = 0; i != row*col; ++i)
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elems[i] = B.elems[i];
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};
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//重载矩阵赋值操作符
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Matrix& Matrix::operator = (Matrix& B)
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{
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if((row != B.row) || (col != B.col))
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throw invalid_argument("The matrix should be matched.");
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row = B.row;
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col = B.col;
150
elems = new double[row*col];
151
for(int i = 0; i != row*col; ++i)
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elems[i] = B.elems[i];
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return *this;
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};
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//重载矩阵相加操作符
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Matrix Matrix::operator+(const Matrix& B)const
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{
160
if((row != B.row) || (col != B.col))
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throw invalid_argument("The matrix should be matched");
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Matrix& T = * new Matrix;
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T.row = row;
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T.col = col;
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T.elems = new double[row*col];
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for(int i = 0; i != row*col; ++i)
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T.elems[i] = elems[i] + B.elems[i];
170
return T;
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};
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//重载矩阵相减操作符
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Matrix Matrix::operator-(const Matrix& B)const
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{
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if((row != B.row) || (col != B.col))
178
throw invalid_argument("The matrix should be matched");
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Matrix& T = * new Matrix;
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T.row = row;
182
T.col = col;
183
T.elems = new double[row*col];
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for(int i = 0; i != row*col; ++i)
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T.elems[i] = elems[i] - B.elems[i];
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return T;
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};
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//重载矩阵相乘操作符
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Matrix Matrix::operator *(const Matrix& B)const
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{
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if( col != B.row)
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throw invalid_argument("The matrix should be matched.");
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Matrix& T = *new Matrix;
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T.row = row;
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T.col = B.col;
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T.elems = new double[T.row * T.col];
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for(int i = 0; i != T.row; ++i)
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for(int j = 0; j != T.col; ++j)
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{
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T.elems[i * T.col + j] = 0;
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for(int k = 0; k != col; ++k)
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T.elems[i * T.col + j] += elems[i * col + k] * B.elems[k*B.col + j];
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}
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return T;
211
};
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//转置矩阵
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Matrix& Matrix::trans()const
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{
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Matrix& T = *new Matrix; //new 返回的是指针,需要解引用
217
T.row = col;
218
T.col = row;
219
T.elems = new double[row*col];
220
for(int i = 0; i != T.row; ++i)
221
for(int j = 0; j != T.col; ++j)
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T.elems[i*T.col + j] = elems[j*col + i];
223
return T;
224
}
1
//Mainfun.cpp
2
//测试编写的矩阵类
3
#include "Matrix.h"
4
#include <iostream>
5
#include <string>
6
#include <fstream>
7
#include <cstdlib>
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#include <stdexcept>
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using namespace std;
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int main()
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{
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double d[12] =
{1,2,3,4,5,6,7,8,1,2,3,4};
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double d2[12] =
{1,2,3,4,1,2,3,4,5,6,7,8};
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Matrix A(3,4,d,12);
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Matrix B(3,4,d2,12);
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Matrix C= B.trans();
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cout << "A = \n" << A << "B = \n" << B << "C = \n" <<C<<endl;
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cout << "A + B \n" << A + B << "B*C \n" << B*C <<endl;
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//将矩阵输出到文件Matrix_out.txt中
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print_file(A,"Matrix_out.txt");
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//从文件"Matrix_in.txt"中读取矩阵
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Matrix D("Matrix_in.txt");
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cout << D <<endl;
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//异常处理的写起来太繁琐了,只示例一个,其他省略了。
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try
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{
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Matrix D(0,3);
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}
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catch(out_of_range& err)
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{
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cerr << err.what() <<endl;
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}
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system("pause");
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return 0;
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}
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