std::span<T,Extent>::front

 

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std::span

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span::span (C++20)

span::operator= (C++20)

Element access

span::front (C++20)

span::back (C++20)

span::operator[] (C++20)

span::data (C++20)

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span::beginspan::cbegin (C++20)(C++23)

span::endspan::cend (C++20)(C++23)

span::rbeginspan::crbegin (C++20)(C++23)

span::rendspan::crend (C++20)(C++23)

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span::first (C++20)

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span::subspan (C++20)

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as_bytesas_writable_bytes (C++20)(C++20)

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dynamic_extent (C++20)

Deduction guides(C++20)

 

constexpr reference front() const;		(since C++20)

Returns a reference to the first element in the span.

Calling front on an empty span results in undefined behavior.

Parameters

(none)

Return value

A reference to the first element.

Complexity

Constant

Notes

For a span c, the expression c.front() is equivalent to *c.begin().

Example

Run this code

#include <iostream>
#include <span>
 
void print(std::span<const int> const data)
{
    for (auto offset{0U}; offset != data.size(); ++offset)
        std::cout << data.subspan(offset).front() << ' ';
    std::cout << '\n';
}
 
int main()
{
    constexpr int data[] { 0, 1, 2, 3, 4, 5, 6 };
    print({data, 4});
}

Output:

0 1 2 3

See also

back (C++20)

access the last element (public member function)