c++ - 在 C++ 中将 << 运算符重载到输出矩阵

Question

您好，我正在尝试重载 << 运算符以便将矩阵输出为表格。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。这是我第一次重载 << 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

在 Matrix.cpp 中重载运算符<<(已编辑)

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;
} 

我仍然收到错误

Answer 1

错误的原因是你有#include "Matrix.cpp"在你的代码中。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> 之前。标题。

你永远不需要 #include一个.cpp文件。如果您这样做是为了解决链接问题，因为运算符 <<已经丢失，修复它的正确方法是在同一个命令上编译你的 cpp 文件，单独编译它们而不链接然后链接，或者将它们作为你的 IDE 项目的单独项目包含(如果你使用的是开发环境) .

请注意，您正在传递 Matrix按值(value)给运营商。这是次优的，因为您的整个矩阵只是为了打印而被复制。通常，您应该将正在打印的项目传递给运算符(operator) <<通过不断的引用:

// 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) {
    ...
}

编辑(感谢您的提示，Mooing Duck!)