no matching function call to error in vector.push_back - c++

Question

I am getting the following error while compiling my C++ program:
error: no matching function for call to 'std::vector<ChainingTable<int>::Record, std::allocator<ChainingTable<int>::Record> >::push_back(ChainingTable<int>::Record*)'
324 | vector_.push_back(new Record(key, value));
The error is coming from the line:
template <class TYPE>
bool ChainingTable<TYPE>::update(const std::string &key, const TYPE &value)
{
if (!keyExists)
{
vector_.push_back(new Record(key, value));
}
}
This is defined for the class:
class ChainingTable : public Table<TYPE>
{
struct Record
{
TYPE data_;
std::string key_;
Record(const std::string &key, const TYPE &data)
{
key_ = key;
data_ = data;
}
};
std::vector<std::vector<Record>> records_;
int capacity_; // capacity of the array
Complete code:
int sz = numRecords();
bool rc = true;
std::hash<std::string> hashFunction;
size_t hash = hashFunction(key);
size_t idx = hash % capacity_;
std::vector<Record> vector_ = records_[idx];
bool keyExists = false;
for (int i = 0; i < vector_.size(); i++)
{
if (vector_[i].key_ == key)
{
vector_[i].data_ = value;
keyExists = true;
}
}
if (!keyExists)
{
vector_.push_back(new Record(key, value));
}
What could be the reason for this?

Answer 1

Your vector is declared to store objects of type Record, not pointers to them (Record *) but you are trying to push result of operator new which returns Record *, just use std::vector::emplace_back instead:
vector_.emplace_back(key, value);
Note: in this line
std::vector<Record> vector_ = records_[idx];
you create a copy and later modify it, seems that you need a reference.
Note2: in your search loop you do not terminate even if you find object already, you should add break into if statement, that will make it more effective.

Answer 2

The problem is that your variable vector_ holds objects of type Record but when you write:
vector_.push_back(new Record(key, value));
You are trying to add a pointer to a Record object in the vector vector_ instead of adding the Record object itself.
You can solve it by writing:
vector_.emplace_back(key, value);
Alternate solution
Note that there is another possible solution which is to use:
vector_.push_back(Record(key, value));
But using emplace_back should be preferred.