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std::span front() method

constexpr reference front() const;

Returns a reference

to the first element in the container.

Undefined Behavior

Calling front() on an empty span is undefined behavior

.

Parameters

(none)

Return value

A reference to the first element.

Complexity

Constant - O(1).

Exceptions

(none)

Notes

For a span s, the expression s.front() is equivalent to *s.begin() and s[0].

Example

Main.cpp
#include <span>
#include <iostream>

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
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Hover to see the original license.

std::span front() method

constexpr reference front() const;

Returns a reference

to the first element in the container.

Undefined Behavior

Calling front() on an empty span is undefined behavior

.

Parameters

(none)

Return value

A reference to the first element.

Complexity

Constant - O(1).

Exceptions

(none)

Notes

For a span s, the expression s.front() is equivalent to *s.begin() and s[0].

Example

Main.cpp
#include <span>
#include <iostream>

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
This article originates from this CppReference page. It was likely altered for improvements or editors' preference. Click "Edit this page" to see all changes made to this document.
Hover to see the original license.