table of contents
std::multimap::begin,(3) | C++ Standard Libary | std::multimap::begin,(3) |
NAME¶
std::multimap::begin, - std::multimap::begin,
Synopsis¶
iterator begin(); (until C++11)
iterator begin() noexcept; (since C++11)
const_iterator begin() const; (until C++11)
const_iterator begin() const noexcept; (since C++11)
const_iterator cbegin() const noexcept; (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.
Example¶
// Run this code
#include <algorithm>
#include <cassert>
#include <iostream>
#include <map>
#include <string>
#include <cstddef>
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)
2022.07.31 | http://cppreference.com |