CODEWITHSUNDEEP
c++arrayspointersvector
codeLover
codeLover

Reputation: 3810

How to Convert a (vector of pointers) --> (Pointer to an array of pointers)

I understand "How to convert vector to array in C++"

answers how to convert a vector of doubles (NON POINTER TYPE) to an array.

My requirement :: To convert (a vector of CustomClass pointers) to (a CustomClass pointer to an array of CustomClass pointers).

Does the following code mean "(vector of pointers) --> (Pointer to an array of CustomClass pointers)" 

std::vector <CustomClass*> vectorObject(SizeOfVector);  // Here each element of the vector //is a pointer to CustomClass object.
CustomClass* customClassArray = &vectorObject[0];

Please correct me if I am wrong. Kindly Help with a code snippet.

Thanks in advance.

Upvotes: 1

Views: 2345

Answers (3)

Blindy
Blindy

Reputation: 67382

Actually vectorObject[0] is a CustomClass *, so &vectorObject[0] is a CustomClass **.

You're making an interesting assumption here, that vector<> stores its elements sequentially. You're probably right though, so your code should work.

Edit: As per Ben Voigt's comments, the contiguousness of vector<> is guaranteed by the standard, so this method will 100% work.

Upvotes: 2

rerun
rerun

Reputation: 25495

Vector is a wrapper in a sorts for an array and provides all the features of an array whilst also allowing the array to grow shrink know how big it is and a lot of other useful features. One of the requirements of std vector is that its data is stored in a contiguous fashion like an array. Because of this requirement you can get an array of elements by taking the address of the first element regardless of type.

std::vector <CustomClass*>vectorObject Means that you have a vector of CustomClass Pointers to get an array

CustomClass **Array = &vectorObject[0] Now I have taken the contiguous data segment at offset 0 in the vector and assigned it the a pointer pointer of customclass remember that arrays and pointers are deeply connected in c and c++ I can now access the pointer pointer as if it were an array

CustomClass * FirstEle = Array[0];

Upvotes: 2

dchhetri
dchhetri

Reputation: 7136

Yes, vectors are required to be consequtive in memory, so the expression "&vectorObject[0]" would return the address of the first element, in which you can point to.

Upvotes: 2

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