How to dynamically allocate array of objects using parameterized constructor?
c++, dynamic-allocation
Solution
You could use placement-new as:
typedef std::aligned_storage<sizeof(SimpleClass),
std::alignment_of<SimpleClass>::value
>::type storage_type;
//first get the aligned uninitialized memory!
SimpleClass *p1 = reinterpret_cast<SimpleClass*>(new storage_type[N]);
//then use placement new to construct the objects
for(size_t i = 0; i < N ; i++)
new (p1+i) SimpleClass(i * 10);
In this example, I'm passing `(i * 10)` to the constructor of `SampleClass`.
- Online Demo
Hope that helps.
Problem
Consider a simple class: ``` class SimpleClass { int a; public: SimpleClass():a(0){} SimpleClass(int n):a(n){} // other functions }; SimpleClass *p1, *p2; p1 = new SimpleClass[5]; p2 = new SimpleClass(3); ``` In this case the default constructor `SimpleClass()` gets called for the construction of newly allocated objects for p1 and the parameterized constructor for p2. My question is: Is it possible to allocate an array and use the parameterized constructor using the new operator? For example, if I want the array to be initialized with objects having variable `a` value being 10, 12, 15, ... respectively, is it possible to pass these values when using the new operator? I know that using stl vector is a better idea to deal with arrays of objects. I want to know whether the above is possible using new to allocate an array.