傳遞不同的函數作爲參數

Question

假設我有這個類：

template<class K, class Compare> 
class findMax { 
    K* keyArray; // Supposed to be an array of K. 
    int size; 

public: 
     findMax (K n, Compare init); // Here I would like to initialize the array. 
     ~findMax(); 

     K& Find(K key, Compare cmp); // Return an elemnt in the array according to a condition. 
     void printArray(Compare print); // Print the array according to a condition. 

}; 

我希望每個cmp函數，當我實現構造，Find和printArray是不同的。
例如：

template<class K, class Compare> 
findMax<K, Compare>::findMax(int n, Compare init) { 
    keyArray = new K [n]; 
    init(keyArray, n); 
} 

其中init是一個功能我在源文件中實現，這樣的例子：

// Init will initialize the array to 0. 
void init (int* array, int n) { 
    for (int i=0; i<n; i++) 
     array[i] = 0; 
} 

雖然，我希望能夠發送不同的功能Find例如，比較兩個元素。我無法弄清楚如何，因爲當我創建一個新的findMax對象，如findMax<int, UNKNOWN> f，我該如何放置而不是UNKNOWN？

Answer 1

試試這個 -

#include <iostream> 
#include <functional> 
using namespace std; 

template<class K, class Compare> 
class findMax { 
    K* keyArray; // Supposed to be an array of K. 
    int size; 

public: 
     findMax (K n, Compare init){init();}; // Here I would like to initialize the array. 
     ~findMax(){}; 
    template<typename Compare1> 
     K& Find(K key, Compare1 cmp){ cmp();}; // Return an elemnt in the array according to a condition. 
     template<typename Compare2> 
     void printArray(Compare2 print){print();}; // Print the array according to a condition. 

}; 
int main() { 
    findMax<int,std::function<void()>> a{5,[](){cout<<"constructor"<<endl;}}; 
    a.Find(5,[](){cout<<"Find"<<endl;}); 
    a.printArray([](){cout<<"printArray";}); 
    return 0; 
}