重载<<运算符以C++输出矩阵

Overloading << operator to output matrix in C++

本文关键字：lt 输出 运算符 重载 C++      更新时间：2023-10-16

嗨，我正试图重载<lt；运算符，以便将矩阵输出为表。我已经开始实现并完成了它，但我不确定我是否做对了，因为我遇到了对我来说没有意义的错误<所以我不确定我是否做对了。请帮忙。

错误（已编辑）：

In file included from MatrixTester.cpp:3:
Matrix.h:16: error: expected ‘;’ before ‘operator’
In file included from MatrixTester.cpp:4:
Matrix.cpp:132: error: ‘std::ostream& Matrix::operator<<(std::ostream&, const Matrix&)’ must take exactly one argument
MatrixTester.cpp: In function ‘int main()’:
MatrixTester.cpp:15: error: no match for ‘operator<<’ in ‘std::cout << matrix’
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/ostream:108: note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& (.....

我的MatrixTester.cpp:

#include "Matrix.h"
#include "Matrix.cpp"
#include<iostream>
#include<vector>
using namespace std;
int main(){
    int row,column;
    cout << "Enter number of rows: ";
    cin >> row;
    cout << "Enter number of column: ";
    cin >> column;
    Matrix matrix(row,column);
    cout<<matrix;
    vector<int> rowVec;
    vector<int> colVec;
    bool cont = true;
    do{
        cout << "Enter column index: ";
        int index;
        cin >> index;
        for(int i = 0; i < row; i++){
            cout << "Enter an integer: ";
            int num;
            cin >> num;
            colVec.push_back(num);  
        }
        if (matrix.setColumn(colVec,index) == false){
            cout << "Unable to modify matrix: Index might be out of bounds " << endl;
        }else{
            cont = false;
        }
    }while(cont == true);
    cout<<matrix;   
    cout << "Enter row index: ";
    int index;
    cin >> index;
    rowVec = matrix.getRow(index);
    for (int i =0;i<rowVec.size();i++){
        cout << rowVec[i] << "  ";
    }
    cout << endl;
    double avg = matrix.average();
    cout<<"Average: " <<avg<<endl;
    Matrix m2(rowVec.size(), colVec.size());
    rowVec = matrix.getRow(1);
    for (int i=0; i <= row-1; i++){
        cout <<"for l" <<endl;
        m2.setRow(rowVec,i);
    }
    cout <<"Adding..." <<endl;
    Matrix m3(row,column); 
    m3 = matrix + m2;
    cout<<m3;
    cout <<"Subtract..." <<endl; 
    m3 = matrix - m2;
    cout<<m3;
    cout <<"Multiply..." <<endl; 
    m3 = matrix * m2;
    cout<<m3;
}

矩阵.h

#ifndef MATRIX_H
#define MATRIX_H 
#include<vector>
using namespace std;
class Matrix{
    public:
        Matrix();
        Matrix(int r, int c);
        bool setRow(vector<int> row, int r);
        bool setColumn(vector<int> col, int c);
        vector<int> getRow(int index);
        vector<int> getCol(int index);
        void indentityMatrix();
        ostream& Matrix operator<<(ostream& out, const Matrix& m);
        double average();
        Matrix operator+(Matrix m);
        Matrix operator-(Matrix m);
        Matrix operator*(Matrix m);
        Matrix operator/(Matrix m);
    private:
        int row, column;
        vector< vector<int> > matrix;
};
#endif

重载运算符<lt；在Matrix.cpp（已编辑）中

ostream& Matrix::operator<<(ostream& out, const Matrix& m){
    vector<int> vecRow;
    for (int i = 0; i < row; i++){
        vecRow = m.getRow(i);
        for (int j = 0; j < row; j++){
            out << vecRow[j];
            out <<"t";
        }
        out << endl;
    }
    return out;
}

我仍然得到错误

错误的原因是您的代码中有#include "Matrix.cpp"。它本身是错误的，但在这种情况下，它也会导致"不完整类型"错误，因为它包含在<iostream>标头之前。

您应该永远不需要#include一个cpp文件。如果您这样做是为了修复链接问题，因为缺少运算符<<，那么修复该问题的正确方法是在同一命令上编译cpp文件，在不链接然后链接的情况下单独编译它们，或者将它们作为IDE项目的单独项包含（如果您使用的是开发环境）。

请注意，您正在按值将Matrix传递给运算符。这是次优的，因为复制整个矩阵只是为了打印。通常，您应该通过常量引用将正在打印的项目传递给操作员<<：

// This goes into the Matrix.h header:
friend std::ostream & operator<<(std::ostream &out, const Matrix& p);
// This goes into Matrix.cpp implementation:
ostream& operator<<(ostream& out, const Matrix& m) {
    ...
}

EDIT（感谢您的提示，Mooing Duck！）

由于dasblinkenlight似乎暂时分心，以下是operator<<应该如何声明和定义：

矩阵.h:

class Matrix{
    public:
        //ostream& Matrix operator<<(ostream& out, const Matrix& m);
        friend ostream& operator<<(ostream& out, const Matrix& m);
};

Matrix.cpp:

ostream& operator<<(ostream& out, const Matrix& m) {
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