C++ Dynamic Memory Allocation

new and delete are essentially the C++ versions of malloc $and free. The difference is that new also calls the appropriate constructor if used on a class type along with allocating the memory and new and delete are keywords rather than functions, so you don't use (...) when calling them.

new usage

#include <iostream>

int main() {
	int *iptr = new int;
	*iptr = 10;
	std::cout << "value of iptr " << iptr << std::endl;
	std::cout << "value in *iptr " << *iptr << std::endl;
	return 0;
}

iptr needs to be freed at some point.

delete usage

int *iptr = new int;
*iptr = 1;
delete ptr;

After delete, the value of iptr becomes 0 and address is changed.

Dynamic array allocation

No size calculations needed: T * fresh = new T[n] allocates an array of n elements of type T.

• If the type T is a built-in type (int, float, char, etc.), then the values are not initialized, like with malloc.
• If T is a class, then T's default constructor is called for each element allocated.

To delete, use delete[] fresh to deallocate a pointer returned by new T[n].

• If T is not a "built-in" type (int, float, char, etc) then the values are not initialized, like with malloc.