Vector in a struct wont let me push_back

Hi i have a vector in a struct as follows for pthreads argument passing:

struct thread_data{
   vector< pair < Database, string> > list_databases;
   ...
   ...
};

...some more code...

then in a later function when i do the following ( mydata is a thread_data passed into the function ) ( entry being a pair< Database, string > )

mydata->list_databases.push_back(entry);

whenever I do this it tells me that push_back is of non-class type. I dont understand the error. I also tried using:

vector< pair<Database,string> > * list_databases;

and

mydata->list_databases->push_back(entry);

and a combination of the two. All give me the same error. Can anyone suggest something? I've researched this and have been stuck on it for hours. Thank you

edit:

Here is the rest of the code:

#include<iostream>
#include<pthread.h>
#include<vector>
#include<string>
#include<fstream>

using namespace std;

struct thread_data{
   vector< pair<Database, string> >* list_databases;
   const char* store;
}

void* load_store( void* threadarg );

int main (){
  vector< pair <Database, string> > list;
  pthread_t thread1;
  string test;
  cout <<"$ ";
  cin >> test;

  const char* store_name = test.c_str();

  struct thread_data tester;
  tester.store = store_name;
  tester.list_databases = &list;

  pthread_create(&thread1,NULL,load_store, (void*) &tester);
  return 0;
}

void * load_store( void* threadarg ){
  struct thread_data *mydata;
  mydata = (struct thread_data*) threadarg;
  string store_used = mydata->store;

  ifstream load;
  string conversion;
  Database Loader;
  load.open(st开发者_如何学Pythonore_used.c_str());

  if(!load){ cerr << "Does not exist" << endl;
    exit(1);
  }

  while(!load.eof()){
    //...pushes file contents into database Loader...
  }
  load.close();
  pair < Database, string > new_store(Loader, store);
  mydata->list_databases->push_back(new_store);     // this is where the error occurs
 return 0;
}

list is a local variable in the main function, so it is destroyed when main returns (on the return 0; line in main). You pass the address of this local variable to load_store, which you start on another thread. If load_store tries to access list after list has been destroyed, bad things happen.

You need to synchronize access to list, probably by having main join with thread1 before exiting.

mydata->list_databases.push_back(entry);, as you've shown in your question, will fail because thread_data::list_databases is a vector<...>* rather than a vector<...>. I.e., it's a pointer-type rather than a class-type, just as the compiler error you're seeing indicates.

mydata->list_databases->push_back(new_store);, as you've shown in your code sample, should work, except that you need to #include <utility> in order to use std::pair.