Thread: array of objects

num objects = sizeof(array)/sizeof(array[0]);

That won't work if the array was declared outside of the current scope (i.e. in another function, as only a pointer to the first element in the array will be passed).

So, you have a couple options:
1. Make sure you only use that method in the proper scope.
2. Keep track of this information in another variable.
3. Use a container such as std::vector.

You can get away with three basic operations using a std::vector. push_back(), size(), and operator[]:

Code:

#include <iostream>
#include <vector>

int main()
{
  std::vector<int> v;

  for ( int i = 0; i < 10; i++ )
    v.push_back ( i );

  for ( int i = 0; i < v.size(); i++ )
    std::cout<< v[i] <<'\n';
}

push_back() appends a new item onto the vector, size() tells you how many items are in the vector, and operator[] makes a vector look like an array for subscripting.

This is all well and good, but the above code will probably give you a warning about a mismatch between signed and unsigned types. That's because size() returns vector<T>::size_type, which is unsigned. You can call that the fourth 'operation':

Code:

#include <iostream>
#include <vector>

int main()
{
  std::vector<int> v;

  for ( int i = 0; i < 10; i++ )
    v.push_back ( i );

  for ( std::vector<int>::size_type i = 0; i < v.size(); i++ )
    std::cout<< v[i] <<'\n';
}

That should suffice until you get to the point where you need more power. But by then you'll know enough to figure out how to use the other member functions of the std::vector class.