std::experimental::erase_if (std::map)
From cppreference.com
< cpp | experimental
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Experimental
Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals TS v2)
Library fundamentals 3 (library fundamentals TS v3)
Extensions for parallelism (parallelism TS)
Extensions for parallelism 2 (parallelism TS v2)
Extensions for concurrency (concurrency TS)
Extensions for concurrency 2 (concurrency TS v2)
Concepts (concepts TS)
Ranges (ranges TS)
Reflection (reflection TS)
Mathematical special functions (special functions TR)
Merged into ISO C++ The functionality described on this page was merged into the mainline ISO C++ standardas of 11/2018, see std::erase_if (since C++20)
Defined in header
<experimental/map>
template< class Key, class T, class Compare, class Alloc, class Pred >
void erase_if( std::map <Key, T, Compare, Alloc>& c, Pred pred );
(library fundamentals TS v2)
void erase_if( std::map <Key, T, Compare, Alloc>& c, Pred pred );
Erases all elements that satisfy the predicate pred from the container. Equivalent to
for (auto i = c.begin(), last = c.end(); i != last;) { if (pred(*i)) i = c.erase(i); else ++i; }
Contents
[edit] Parameters
c
-
container from which to erase
pred
-
predicate that determines which elements should be erased
[edit] Complexity
Linear.
[edit] Example
Run this code
#include <experimental/map> #include <iostream> template<typename Os, typename Container> inline Os& operator<<(Os& os, Container const& cont) { os << '{'; for (const auto& item : cont) os << '{' << item.first << ", " << item.second << '}'; return os << '}'; } int main() { std::map <int, char> data{{1, 'a'},{2, 'b'},{3, 'c'},{4, 'd'}, {5, 'e'},{4, 'f'},{5, 'g'},{5, 'g'}}; std::cout << "Original:\n" << data << '\n'; std::experimental::erase_if(data, [](const auto& item) { return (item.first & 1) == 1; }); std::cout << "Erase items with odd keys:\n" << data << '\n'; }
Output:
Original:
{{1, a}{2, b}{3, c}{4, d}{5, e}}
Erase items with odd keys:
{{2, b}{4, d}}