Using std::vector as view on to raw memory

Question

I\'m using a external library which at some point gives me a raw pointer to an array of integers and a size.

Now I\'d like to use std::vector to access and

Answer 1

Since the algorithm-library works with iterators you can keep the array.

For pointers and known array length

Here you can use raw pointers as iterators. They support all the opertations an iterator supports (increment, comparison for equality, value of, etc...):

#include 
#include 

int *get_data_from_library(int &size) {
    static int data[] = {5,3,2,1,4}; 

    size = 5;

    return data;
}


int main()
{
    int size;
    int *data = get_data_from_library(size);

    std::sort(data, data + size);

    for (int i = 0; i < size; i++)
    {
        std::cout << data[i] << "\n";
    }
}

data points to the dirst array member like an iterator returned by begin() and data + size points to the element after the last element of the array like an iterator returned by end().

For arrays

Here you can use std::begin() and std::end()

#include 
#include 

int main()
{
    int data[] = {5,3,2,1,4};         // raw data from library

    std::sort(std::begin(data), std::end(data));    // sort raw data in place

    for (int i = 0; i < 5; i++)
    {
        std::cout << data[i] << "\n";   // display sorted raw data 
    }
}

But keep in mind that this only works, if data does not decay to a pointer, because then length information goes missing.