Question

嘿，我创建了一个名为＆＃34; Node＆＃34;的抽象类。以及实现Node类的NodeBlock类。在我的主类中，我需要打印NodeBlock中的值，这是我的主类的一些代码：

 //receving the fasteset route using the BFS algorithm.
std::stack<Node *> fast = bfs.breadthFirstSearch(start, goal);

/*print the route*/
while (!fast.empty()) {
    cout << fast.top() << endl;
    fast.pop();
}

节点：

#include <vector>
#include "Point.h"
#include <string>

using namespace std;

/**
 * An abstract class that represent Node/Vertex of a graph the node
 * has functionality that let use him for calculating route print the
 * value it holds. etc..
 */
    class Node { 
    protected:
        vector<Node*> children;
        bool visited;
        Node* father;
        int distance;

    public:
        /**
         * prints the value that the node holds.
         */
        virtual string printValue() const = 0;

        /**
         * overloading method.
         */
        virtual string operator<<(const Node *node) const {
            return printValue();
        };

    };

NodeBlock.h：

    #ifndef ADPROG1_1_NODEBLOCK_H
#define ADPROG1_1_NODEBLOCK_H

#include "Node.h"
#include "Point.h"
#include <string>


/**
 *
 */
class NodeBlock : public Node {
private:
    Point point;

public:    
    /**
     * prints the vaule that the node holds.
     */
    ostream printValue() const override ;
};
#endif //ADPROG1_1_NODEBLOCK_H

NodeBlock.cpp：

    #include "NodeBlock.h"
using namespace std;



NodeBlock::NodeBlock(Point point) : point(point) {}

string NodeBlock::printValue() const {
    return   "("  + to_string(point.getX()) + ", " + to_string(point.getY());
}

我删除了那些类的所有不必要的方法。现在我试图重载＆lt;＆lt;运算符所以当我从堆栈顶部。（）它将并将其分配给＆＃34; cout＆＃34;它会打印该点的字符串。

但我目前的输出是： 0x24f70e0 0x24f7130 0x24f7180 0x24f7340 0x24f7500

你知道的是地址。谢谢你的帮助

Answer 1

您正在寻找的是ostream运算符，其左侧为Node，右侧为ostream，并且评估为Node std::ostream& operator<<(std::ostream& out, const Node& node) { out << node.printValue(); return out; } }。因此，它应该像这样定义（在cout类之外）：

Node

然后你需要确保Node* cout << *fast.top() << endl; // dereference the pointer而不是DATETIME：

MariaDB [test]> create table t (t timestamp, d datetime);
Query OK, 0 rows affected (0.59 sec)

MariaDB [test]> insert into t values ('2850-12-01 00:00:00','2850-12-01 00:00:00');
Query OK, 1 row affected, 1 warning (0.08 sec)

MariaDB [test]> select * from t;
+---------------------+---------------------+
| t                   | d                   |
+---------------------+---------------------+
| 0000-00-00 00:00:00 | 2850-12-01 00:00:00 |
+---------------------+---------------------+
1 row in set (0.00 sec)

字符串重载运算符＆＃34;＆gt;＆gt;＆＃34;

1 个答案: