I have array of pointers:
private:
LimitOrder* orders[Size];
In constructor i'm trying to fill it with NULL:
InternalIdAssigner::InternalIdAssigner(void):
lastCleanId(0)
{
std::fill(orders, orders + Size, NULL);
But this doesn't work, I receive error: error C2440: '=' : cannot convert from 'const int' to 'LimitOrder *'
What is the right way to fill array field with NULL?
The error message is kind of clear, if you understand what NULL really is: a literal 0.
When you pass 0 to a template, the deduced type is int, not a pointer type. While a literal 0 is implicitly convertible to any pointer type and will be a null pointer, after it if passed to fill it is just an int with value 0, which is not convertible to a pointer type.
In C++11 you could and should use nullptr instead of NULL. In C++03 you can also convert the pointer to the destination type:
std::fill(orders, orders + Size, static_cast<LimitOrder*>(0));
But then again, why go through the process in the first place when you can zero-initialize the array in the initializer list?
InternalIdAssigner::InternalIdAssigner()
: lastCleanId(), orders() {}
If you're using C++11:
std::fill(orders, orders + Size, nullptr);
otherwise:
std::fill(orders, orders + Size, static_cast<LimitOrder*>(NULL));
Or if you don't want to use a cast:
LimitOrder* tmp = NULL;
std::fill(orders, orders + Size, tmp);
My suggestion:
Change
std::fill(orders, orders + Size, NULL);
to
std::fill(orders, orders + Size, (LimitOrder*)NULL);
orders()to your initializer list.