来自类的c++第二个函数无法访问第一个

Question

我的代码将整数存储在 [n] x [n] 矩阵中。但是当我使用我的 printMatrix() 方法时，它在命令提示符下只返回零，而不是我之前分配给矩阵的整数。我想我必须使用引用/指针，但我不太确定如何使用。这是我的代码:

#include <iostream>
#include <vector>

using namespace std;

class Matrices
{
public:
    Matrices();
    void storeMatrix(vector <vector <int> > matr, int n);
    void printMatrix(vector <vector <int> > matr, int n);

private:
    int n;
    vector <vector <int> > matr;
    int cell;
};//class Matrices
Matrices::Matrices()
{

}//Constructor

void Matrices::storeMatrix(vector <vector <int> > matr, int n)
{
    for( int i = 0; i < n; i++)
        {
            for(int j = 0; j < n; j++)
            {
                cout << "Please insert an int for matr [" << i << "] [" << j << "]" << endl;
                cin >> cell;
                matr[i][j] = cell;
            }
        }


}//storeMatrix

void Matrices::printMatrix(vector <vector <int> > matr, int n)
{
    for( int i = 0; i < n; i++)
        {
            for(int j = 0; j < n; j++)
            {
                cout << matr[i][j];
            }
            cout<<endl;
        }
}//printMatrix


int main()
{
    int m;
    cin >> m;
    int n = 1;

    for (int i = 1; i <= m; i++)  // loop to make the input integer equivalent to power of 2;
        n = n * 2;

    vector <vector <int> > matr (n , vector <int> (n));
    Matrices k;
    k.storeMatrix(matr, n);
    k.printMatrix(matr, n);


    return 0;
}

有什么办法解决吗？

Answer 1

删除与printMatrix()相关的所有参数.在 main() 及其原型(prototype)(在类内)及其定义中 void YourClassName::printMatrix() .然后在其定义中设置:

cout << this->matr[i][j];//请参阅下面的进一步说明

而不是这个:

cout << matr[i][j];

添加This将打印您已在上一个函数中填充数据的“当前实例”的私有(private)成员。

也在你的store()您需要“链接”您正在对当前实例执行的操作。

总体:此设计应该可以帮助您更好地理解正在发生的事情。看这个 main():

int main()
{
    int m;
    int n = 1;

    cin >> m;

    Matrices k(m, n); // create an object k
    k.storeMatrix(); // store matrix for "this" object k 
    k.printMatrix(); // print matrix of "this" object k 

    return 0;
}

然后看看类:

class Matrices
{
public:
    Matrices();
    Matrices(int, int);
    void storeMatrix();
    void printMatrix();

private:
    int n;
    vector <vector <int> > matr;
    int cell;
};//class Matrices

Matrices::Matrices() 
{}

Matrices::Matrices(int m, int n)
{
    for (int i = 1; i <= m; i++)  // loop to make the input integer equivalent to power of 2;
        n = n * 2;

    vector <vector <int> > _matr (n, vector <int>(n));
    this->matr = _matr;

}//Constructor

void Matrices::storeMatrix()
{
    for (int i = 0; i < this->matr.size(); i++)
    {
        for (int j = 0; j < this->matr[i].size(); j++)
        {
            cout << "Please insert an int for matr [" << i << "] [" << j << "]" << endl;
            cin >> cell;
            this->matr[i][j] = cell; //whatever "this" object is, store its matrix
        }
    }
}//storeMatrix

void Matrices::printMatrix()
{
    for (int i = 0; i < this->matr.size(); i++)
    {
        for (int j = 0; j < this->matr[i].size(); j++)
        {
            cout << this->matr[i][j]; // whatever "this" objecct is, print its matrix
        }
        cout << endl;
    }
}//printMatrix