malloc
is a C function - it shouldn't be used with C++ objects, which is very well explained here (short answer: in C++, when you are not dealing with POD types, std::list
in your case, you must call the object's constructor to have the actual object ready for use, and malloc()
does not do that).
You should used new
instead. While malloc
only allocates a block of memory of size vertex
, new
does that and also initializes std::list
aswell by calling it's constructor (interesting to point out that when you call delete()
, you are calling your object's desctructor aswell).
Here is a piece of code that works for your case, although I suggest you to start using more C++ features within C++ projects:
#include <iostream>
#include <list>
#include <cstdlib>
#include <new>
using namespace std;
// structure to represent a vertex(node) in a graph
typedef struct vertex{
int info;
list<int> adj; // adjacency list of edges contains the indexes to vertex
} *vPtr;
int main(){
cout << "allocating memory for our vertex struct... \n";
vPtr node = new vertex();
node->info = 34; // some arbitrary value
(node->adj).push_back(2); // trying to insert a value in the list
cout << "cleaning allocated memory... \n";
delete(node);
return 0;
}