[C++] erase/erase_if

개요

• erase
  • 값이 같은 요소를 삭제하는 함수
  • 삭제된 수를 반환
• erase_if
  • 조건을 충족하는 요소를 삭제하는 함수
  • 삭제된 수를 반환

예제

• 코드

   #include <iostream>
   #include <list>
   #include <map>
   #include <string>
   #include <type_traits>
   #include <vector>
      
   using namespace std;
      
   int main() {
   	auto print = [](auto elements) {
   		for (const auto &iter : elements) {
   			if constexpr (is_same_v<map<int, string>, decltype(elements)>) {
   				cout << iter.first << " ";
   			} else {
   				cout << iter << " ";
   			}
   		}
   		cout << endl;
   	};
      
   	auto erase_test = [print]() {
   		vector<int> v = {1, 2, 3, 4, 5, 5, 6};
   		print(v);
   		cout << erase(v, 5) << endl;
   		print(v);
      
   		cout << endl;
      
   		list<int> l = {1, 2, 3, 4, 5, 5, 6};
   		print(l);
   		cout << erase(l, 5) << endl;
   		print(l);
   	};
   	erase_test();
      
   	cout << endl << "------" << endl << endl;
      
   	auto erase_if_test = [print]() {
   		vector<int> v = {1, 2, 3, 4, 5, 6};
   		print(v);
   		cout << erase_if(v, [](int i) { return i % 2 == 0; }) << endl;
   		print(v);
      
   		cout << endl;
      
   		map<int, string> m = {{1, "a"}, {2, "b"}, {3, "c"}};
   		print(m);
   		cout << erase_if(m, [](auto &item) {
   			auto &[key, value] = item;
   			return key % 2 == 0;
   		}) << endl;
   		print(m);
   	};
   	erase_if_test();
      
   	return 0;
   }
  

• 실행 결과

   1 2 3 4 5 5 6
   2
   1 2 3 4 6
      
   1 2 3 4 5 5 6
   2
   1 2 3 4 6
      
   ------
      
   1 2 3 4 5 6
   3
   1 3 5
      
   1 2 3
   1
   1 3