虚函数没有被覆盖[关闭]

Question

我不知道为什么我的虚函数没有被覆盖，在网上查找示例时我无法发现我做错了什么，我一定是遗漏了一些东西。

基类

class HashTable {
// removed some unrelated functions and data to keep this page short

void Insert(int key, HashTable *htable)
    {
        int pos = Find(key, htable);
        if (htable->table[pos].info != Legitimate)
        {
            htable->table[pos].info = Legitimate;

            int rKey = Reverse(key);

            htable->table[pos].element = rKey;
        }
    }

virtual int Find(int key, HashTable *htable)
    {
        return 0;
    }
};

儿童班

class SingleHash : public HashTable {

     int Find(int key, HashTable *htable)
    {
        int hashVal = HashFunc1(key, htable->size);

        while (htable->table[hashVal].info != Empty &&
            htable->table[hashVal].element != key)
        {
            hashVal = hashVal;
            hashVal = hashVal % htable->size;

            prob = prob + 1;
        }

        trackProbes(prob);
        return hashVal;

    }
};

class DoubleHash : public HashTable {

     int Find(int key, HashTable *htable)
    {
        int hashVal = HashFunc1(key, htable->size);
        int stepSize = HashFunc2(key, htable->size);

        while (htable->table[hashVal].info != Empty &&
            htable->table[hashVal].element != key)
        {
            hashVal = hashVal + stepSize;
            hashVal = hashVal % htable->size;

            prob = prob + 1;
        }

        trackProbes(prob);
        return hashVal;

    }
};

我的主干是什么样子的

int main()
{
int value, size, pos, i = 1;
    int choice = 1;

    HashTable *htable = new SingleHash;

    cin >> value;

    htable->Insert(value, htable);

    // more unrelated stuff   
}

当我运行我的程序时，它只会在我调用 Insert 时返回基类 (0) 中的内容。

Answer 1

您提供的代码中存在编译错误，例如您未声明为基础的公共函数。

我尝试为你制作 MCVE，它似乎工作正常。

#include <iostream>
using namespace std;
class HashTable {
public:
    void Insert(int x)   {
      Find(x);
    }
    virtual int Find(int x)    {
        cout<<"base hash find \n";
        return x;    }
};

class SingleHash : public HashTable {
public:
     int Find(int x)    {
        cout<<"single hash find \n";      
        return x*2;
    }
};

class DoubleHash : public HashTable {
public:
     int Find(int x)    {
        cout<<"DOuble hash find \n";      
        return x*3;    }
};
int main(int argc, char** argv)
{
    int value;
    HashTable *hsingle = new SingleHash;
    cin >> value;
    hsingle->Insert(value);
    HashTable *hdouble = new DoubleHash;
    hdouble->Insert(value);
    return 0;
}

输出是：

单个哈希查找

双哈希查找