`<span>`

Artikkeli
10/25/2022

A span is a view over a contiguous sequence of objects. It provides fast and bounds-safe access. Unlike vector or array, it doesn't "own" the elements.

See span class for detailed information. Here's an example of how to use a span:

#include <span>
#include <iostream>

void Show(std::span<int> someValues)
{
    // show values in reverse
    for (auto rIt = someValues.rbegin(); rIt != someValues.rend(); ++rIt)
    {
        std::cout << *rIt;
    }

    // show a subspan
    for (auto& i : someValues.subspan(1, 2))
    {
        std::cout << i;
    }
}

int main()
{
    int numbers[]{ 0,1,2,3,4 };
    Show(numbers); // note conversion from array to span
}

Requirements

Header: <span>

Namespace: std

Compiler option: /std:c++20 or later is required.

Members

Classes

Name	Description
`span`	Provides a view over a contiguous sequence of objects.

Operators

Name	Description
`operator=`	Span assignment
`operator[]`	Element access

Functions

Name	Description
`as_bytes`	Get the underlying read-only bytes of the span.
`as_writable_bytes`	Get the underlying bytes of the span.

Constants

Name	Description
`dynamic_extent`	Indicates that the span size is determined at runtime rather than compile time. When the number of elements in the span is known at compile time, it's specified as the `Extent` template parameter. When the number isn't known until runtime, specify `dynamic_extent` instead.

Jaa