So, I have a class with a constructor which assigns a random values some of its members. However, from what I can tell, when you allocate a vector of objects, it creates one object then assigns a copy of that object to every object in the vector.
Perhaps some example source code will explain:
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <vector>
using namespace std;
class Foo
{
public:
Foo() : x(rand()%500) { }
int getX() { return x; }
private:
int x;
};
int main()
{
srand( time(NULL) );
Foo f[5];
for ( int i = 0; i < 5; i++ )
{
cout << "x = " << f.getX() << ", ";
}
cout << endl;
vector<Foo> f2(5);
for ( int i = 0; i < f2.size(); i++ )
{
cout << "x = " << f2.getX() << ", ";
}
return 0;
}
The output of the above will be something like (obviously with randomness)
x = 214, x = 86, x = 258, x = 442, x = 391,
x = 262, x = 262, x = 262, x = 262, x = 262,
You can see that when using the vector, the constructor is only called once and then the values are copied into each element.
Now, I know I can solve this by using an initialization function instead. Or perhaps by writing a copy constructor which re-randomizes the variable on copy (though I'd prefer not to do this as I feel a copy should merely copy the values, unless dealing with pointers).
Is there some other method that I am overlooking or some trick to the STL vector to get what I want? Or do I just need to suck it up and use an initialization function?
