Question

我不知道为什么这段代码不起作用......

#include <iostream>

using namespace std;

struct Triple {int row, col, value;};

class Matrix;

class MatrixNode 
{
friend class Matrix;
friend istream& operator>>(istream&, Matrix&);
private:
    MatrixNode *down, *right;
    bool head;
    union {
        MatrixNode *next;
        Triple triple;
    };
    MatrixNode(bool, Triple*);
};

MatrixNode::MatrixNode(bool b, Triple* t)
{
    head = b;
    if (b) {right = down = this;}
    else triple = *t;
}

class Matrix {
friend istream& operator>>(istream&, Matrix&);
public:
    ~Matrix();
private:
    MatrixNode *headnode;
};

istream& operator>>(istream& is, Matrix& matrix)
{
    Triple s;
    cout << "Enter the numbers of row, colume, value" << endl;
    is >> s.row >> s.col >> s.value;

    int p = max(s.row, s.col);

    matrix.headnode = new MatrixNode(false, &s);
    if (p == 0) { matrix.headnode->right = matrix.headnode; return is;}
    MatrixNode **head = new MatrixNode*[p];
    for (int i = 0; i < p; i++)
        head[i] = new MatrixNode(true, 0);
    int currentRow=0;
    MatrixNode *last = head[0];

    for (int i = 0; i < s.value; i++)
    {
        Triple t;
        cout << "Enter the terms" << endl;
        is >> t.row >> t.col >> t.value;
        if (t.row > currentRow){
            last -> right = head[currentRow];
            currentRow = t.row;
            last = head[currentRow];
        }
        last = last -> right = new MatrixNode(false, &t);
        head[t.col]->next = head[t.col]->next->down = last;
    }

    last -> right = head[currentRow];
    for (int i = 0; i < s.col; i++)
        head[i] -> next -> down = head[i];
    for(int i = 0; i < p - 1; i++)
        head[i] -> next = head[i+1];
    head[p-1] -> next = matrix.headnode;
    matrix.headnode -> right = head[0];
    delete [] head;
    return is;
}


int main()
{
    Matrix *a = new Matrix;
    Matrix *b = new Matrix;

    cin >> *a;
    cin >> *b;

}

Answer 1

具体问题是head[t.col]->next未初始化，而您正在取消引用它。

更普遍的问题是你咬的比你嚼得多。你正试图建立一个远远超出你能力的东西，而你正试图一步到位。尝试构建一个更简单的链表，例如，没有联合的链表，没有运算符＆gt;＆gt;和只有一个维度，而不是三个。一旦您对此感到满意，就可以通过小步骤逐步完成更高级的结构。

为什么不执行此链表代码？

1 个答案: