C ++分段在进行矩阵乘法时出错

Question

我试图执行这个代码，它重载一个*运算符，将2矩阵矩阵1和矩阵2相乘并存储在矩阵3中。我可以使用PrintVector（）函数打印矩阵，尽管代码到达重载函数时（它成功打印“Reached here”语句我得到了一个分段错误。一直试图弄清楚这一点，我看不出有什么不对。

#include <iostream>
#include<string>
#include <vector>
using namespace std;

class Class1
{
public:
    vector<vector<int> > matrix;

    Class1(vector<vector<int> > p):matrix(move(p)){}

    //This function is used to perform the multiplication operation between two square matrices
    Class1 operator*(const Class1 &mat1)
     {
        int count = 0;
        vector<vector<int> >  tmp;
        for(int i=0;i<4;i++)
        {
           for(int j=0;j<4;j++)
           {

              tmp[i][j]=0;
              for(int k=0;k<4;k++)
              {
                  cout<<count++<<endl;
                 tmp[i][j]=tmp[i][j]+(matrix[i][k]*mat1.matrix[k][j]);
                 cout<<tmp[i][j]<<" ";
              }
           }
        }
        return tmp;
     }

    void PrintVector()
    {
        for(int i=0;i<4;i++)
        {

            for(int j=0;j<4;j++)
            {
                cout<<matrix[i][j]<<"  ";
            }
            cout<<endl;
        }
        cout<<endl;
    }

};

int main()
{
    Class1 Matrix1 =   {{{ 1, 2, 3, 4 },
                       { 5, 6, 6, 8 },
                       { 9, 8, 7, 6 },
                       { 3, 2, 1, 1 } }};

    Class1 Matrix2 =   Matrix1;

    cout<<"Reached here"<<endl;
    Class1 Matrix3 = Matrix1 * Matrix2;

    Matrix3.PrintVector();

    return 0;
}

Answer 1

好的，所以我需要做的就是重新调整tmp。谢谢@Igor Tandetnik

#include <iostream>
#include<string>
#include <vector>
using namespace std;



class Class1
{
public:
    vector<vector<int> > matrix;

    Class1(vector<vector<int> > p):matrix(move(p)){}

    //This function is used to perform the multiplication operation between two square matrices
    Class1 operator*(const Class1 &mat1)
     {
        int count = 0;
        vector<vector<int> >  tmp;

        tmp.resize(4);
        for(int t=0;t<4;t++)
            tmp[t].resize(4);
        for(int i=0;i<4;i++)
        {
           for(int j=0;j<4;j++)
           {

              tmp[i][j]=0;
              for(int k=0;k<4;k++)
              {
                  cout<<count++<<endl;
                 tmp[i][j]=tmp[i][j]+(matrix[i][k]*mat1.matrix[k][j]);
                 cout<<tmp[i][j]<<" ";
              }
           }
        }
        return tmp;
     }

    void PrintVector()
    {
        for(int i=0;i<4;i++)
        {

            for(int j=0;j<4;j++)
            {
                cout<<matrix[i][j]<<"  ";
            }
            cout<<endl;
        }
        cout<<endl;
    }

};

int main()
{
    Class1 Matrix1 =   {{{ 1, 2, 3, 4 },
                       { 5, 6, 6, 8 },
                       { 9, 8, 7, 6 },
                       { 3, 2, 1, 1 } }};

    Class1 Matrix2 =   Matrix1;

    cout<<"Reached here"<<endl;
    Class1 Matrix3 = Matrix1 * Matrix2;

    Matrix3.PrintVector();

    return 0;
}