make_unchecked_array_iterator

Artikel
07/29/2015

Creates an unchecked_array_iterator that can be used by other algorithms.

Note

This function is a Microsoft extension of the Standard C++ Library. Code implemented by using this function is not portable to C++ Standard build environments that do not support this Microsoft extension.

template <class Iter>
  unchecked_array_iterator<Iter> 
    make_unchecked_array_iterator(
      Iter Ptr
);

Parameters

Ptr
A pointer to the destination array.

Return Value

An instance of unchecked_array_iterator.

Remarks

The make_unchecked_array_iterator function is defined in the stdext namespace.

This function takes a raw pointer and wraps it in a class that performs no checking and therefore optimizes away to nothing, but it also silences compiler warnings such as C4996. Therefore, this is a targeted way to deal with unchecked-pointer warnings without globally silencing them or incurring the cost of checking. For more information and code examples, see Checked Iterators.

Example

In the following example, a vector is created and populated with 10 items. The contents of the vector are copied into an array by using the copy algorithm, and then make_unchecked_array_iterator is used to specify the destination.

// make_unchecked_array_iterator.cpp
// compile with: /EHsc /W4 /MTd

#include <algorithm>
#include <iterator> // stdext::make_unchecked_array_iterator
#include <iostream>
#include <vector>
#include <string>

using namespace std;

template <typename C> void print(const string& s, const C& c) {
    cout << s;

    for (const auto& e : c) {
        cout << e << " ";
    }

    cout << endl;
}

int main()
{
    const size_t dest_size = 10;
    int *dest = new int[dest_size];
    vector<int> v;

    for (int i = 0; i < dest_size; ++i) {
        v.push_back(i);
    }
    print("vector v: ", v);

    // COMPILER WARNING SILENCED: stdext::unchecked_array_iterator is marked as checked in debug mode
    // (it performs no checking, so an overrun will trigger undefined behavior)
    copy(v.begin(), v.end(), stdext::make_unchecked_array_iterator(dest));

    cout << "int array dest: ";
    for (int i = 0; i < dest_size; ++i) {
        cout << dest[i] << " ";
    }
    cout << endl;

    delete[] dest;
}

Output

vector v: 0 1 2 3 4 5 6 7 8 9
int array dest: 0 1 2 3 4 5 6 7 8 9

Requirements

Header: <iterator>

Namespace: stdext

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