NAME¶

std::multimap::begin, - std::multimap::begin,

Synopsis¶

iterator begin(); (1) (noexcept since C++11)
const_iterator begin() const; (2) (noexcept since C++11)
const_iterator cbegin() const noexcept; (3) (since C++11)

Returns an iterator to the first element of the multimap.

If the multimap is empty, the returned iterator will be equal to end().

range-begin-end.svg

Parameters¶

(none)

Return value¶

Iterator to the first element.

Complexity¶

Constant.

Notes¶

libc++ backports cbegin() to C++98 mode.

Example¶

// Run this code

#include <algorithm>
#include <cassert>
#include <cstddef>
#include <iostream>
#include <map>
#include <string>

int main()
{
auto show_node = [](const auto& node, char ending = '\n')
{
std::cout << "{ " << node.first << ", " << node.second << " }" << ending;
};

std::multimap<std::size_t, std::string> mmap;
assert(mmap.begin() == mmap.end()); // OK
assert(mmap.cbegin() == mmap.cend()); // OK

mmap.insert({ sizeof(long), "LONG" });
show_node(*(mmap.cbegin()));
assert(mmap.begin() != mmap.end()); // OK
assert(mmap.cbegin() != mmap.cend()); // OK
mmap.begin()->second = "long";
show_node(*(mmap.cbegin()));

mmap.insert({ sizeof(int), "int" });
show_node(*mmap.cbegin());

mmap.insert({ sizeof(short), "short" });
show_node(*mmap.cbegin());

mmap.insert({ sizeof(char), "char" });
show_node(*mmap.cbegin());

mmap.insert({{ sizeof(float), "float" }, { sizeof(double), "double"}});

std::cout << "mmap = { ";
std::for_each(mmap.cbegin(), mmap.cend(), [&](const auto& n) { show_node(n, ' '); });
std::cout << "};\n";
}

Possible output:¶

{ 8, LONG }
{ 8, long }
{ 4, int }
{ 2, short }
{ 1, char }
mmap = { { 1, char } { 2, short } { 4, int } { 4, float } { 8, long } { 8, double } };

See also¶

end returns an iterator to the end
cend (public member function)
(C++11)
begin
cbegin returns an iterator to the beginning of a container or array
(C++11) (function template)
(C++14)