No matching function on hashtable

Question

When I try to call the create hash function from the following lines of code I receive the error no matching function for call

 myHash.create("5", "Data");
 checkTest("testSimpleIntHash #1", "Data", myHash.retrieve("5"));

The idea is that create receives the key from the KeyValuePair class and then the method would hash the key, go to that bucket, and then insert the key value pair. I believe I am receiving this error because I am not outputting to string. However, I can not figure out the syntax to properly output the key value pair to string with the create method. (I am using std::list, and my KeyValuePair class is functioning properly)

template<typename T> class HashTable
 {
 public:

     static const unsigned int NUM_BUCKETS = 100000;

     HashTable create(const string& key, const T& item) 
     {
         int temp = hash(key);
         arr[NUM_BUCKETS].push_back(KeyValuePair<T>(temp, item));
     }
 private:
     int hash(const string& key) const;
     //Make an array of linked lists of KeyValuePair objects.
     list<KeyValuePair<T>> arr[NUM_BUCKETS];
 };

 template <typename T>
 int HashTable<T>::hash(const string& key) const {
     int temp = 0;
     for (int i = key.length(); i >= 0; i--) {
         temp = (13 * temp + key[i]) % NUM_BUCKETS;
     }
     return temp;
 }

In `create` you are not returning a value, and the class declaration is incoplete(missing class name) — Rama, Mar 20 '17 at 19:23
HashTable myHash; bool checkTest(string testName, string whatItShouldBe, string whatItIs) — T3nt4c135, Mar 20 '17 at 20:08

Rama · Accepted Answer · 2017-03-20T20:13:42.223

In the create method you can return a reference to the class itself.

HashTable& create(const string& key, const T& item) 
 {
     int temp = hash(key);
     arr[NUM_BUCKETS].push_back(KeyValuePair<T>(temp, item));
     return *this;
 }

But anyway, you are not usign it.

And you need to declare the retrievemethod in your class HashTable: For example:

string retrieve(const string& input) 
 {
     string result;
     //Not sure wath do you pretend to be this method.
     //But it will transform your input in your result
     return result;
 }

No matching function on hashtable

1 Answers1