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  1. #include <iostream>
  2. #include <vector>
  3. #include <string>
  4. using namespace std;
  5.  
  6. struct node{
  7.    string val1;
  8.    string val2;
  9.    vector<node *> connectedNodes;
  10. };
  11.  
  12. int compareNode(node a,node b){
  13.  //describe the compare
  14.  return a.val2.compare(b.val2); // or any other code
  15. }
  16.  
  17. template <class T>
  18. class PQueue {
  19.   protected:
  20.     // this declares a private member named compareFunction of type pointer to a function which takes 2 T parameters and returns a int. Note that all the parenthesis are mandatory
  21.     int (*compareFunction)(T, T);
  22.  
  23.   public:
  24.  
  25.     PQueue (int (*compareFunctionParameter)(T, T)) : compareFunction(compareFunctionParameter) {
  26.        // this constructor receives a pointer to function and initializes it's member to that pointer. If the constructor initialization list confuses you, you can read 'compareFunction = compareFunctionParameter '
  27.     }
  28.  
  29.   int someMethod() {
  30.      // call the function through the pointer you have:
  31.      node n1, n2;
  32.      n1.val1 = "node1_val1";
  33.      n1.val2 = "zzz";
  34.  
  35.      n2.val1 = "node2_val1";
  36.      n2.val2 = "aaa";
  37.      return compareFunction(n1, n2);
  38.   }
  39. };
  40.  
  41. int main() {
  42. 	PQueue<node> pq(compareNode);
  43. 	cout <<	pq.someMethod() << endl;
  44. 	return 0;
  45. }
  46.  
Success #stdin #stdout 0s 3432KB
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https://ideone.com/EPjbya
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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