How can I declare an array inside a function according to the size of a parameter?

Question

Here is what I have tried:

int fun1(vector s)
{ 
    const int n = s.size();
    int arr[n]; //<----want to declare an array of length s.size()         


        

Answer 1

For this, C++ has std::vector(n), which retains most of the semantics of a traditional C array but also adds a lot of benefits (dynamic allocation being one, resizing is another, algorithm support is yet another one). Even when your underlying code requires a C array, you can still use the vector and pass an address of the first element down (they are guaranteed to be contiguous).

Typically, std::vector uses heap for underlying storage, so on one hand you are better protected from stack overflows (pun intended), on the other hand, your code now uses dynamic allocation.