【STL】常用的operator classes

void test_plus(){// 數組與數組之間求和int first[] = {1, 2, 3, 4, 5};int second[] = {10, 20, 30, 40, 50};int results[5];transform(first, first + 5, second, results, std::plus<int>());std::copy(first, first + 5, std::ostream_iterator<int>(std::cout, " "));std::cout << std::endl;// 數組累計求和int i[] = {1, 2, 3, 4, 5, 6};int sum(0);sum = accumulate(i, i + 6, 0, std::plus<int>());std::cout << "The result of 1 + 2 + 3 + 4 + 5 + 6 = " << sum << std::endl;}void test_minus(){int numbers[] = {10, 20, 30};int result;result = accumulate(numbers, numbers + 3, 100, std::minus<int>());std::cout << "The result of 100 - 10 - 20 - 30 = " << result << std::endl;}void test_multi(){int numbers[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};int result;result = accumulate(numbers, numbers + 10, 1, std::multiplies<int>());std::cout << "The result of 1*2*3*4*5*6*7*8*9*10 = " << result << std::endl;// 可以做成階乘int factorials[10];partial_sum(numbers, numbers + 10, factorials, std::multiplies<int>());std::copy(factorials, factorials + 10, std::ostream_iterator<int>(std::cout, "\n"));// for (int i = 0; i < 10; ++i)// std::cout << numbers[i] << "! is " << factorials[i] << std::endl;}void test_divides(){int first[] = {10, 40, 90, 40, 10};int second[] = {1, 2, 3, 4, 5};int results[5];transform(first, first + 5, second, results, std::divides<int>());std::copy(results, results + 5, std::ostream_iterator<int>(std::cout, " "));std::cout << std::endl;}void test_greater(){int numbers[] = {10, 40, 90, 50, 20};std::vector<int> v(numbers, numbers + 5);std::sort(v.begin(), v.end(), std::greater<int>());std::copy(v.cbegin(), v.cend(), std::ostream_iterator<int>(std::cout, " "));}// logical_and, logical_or, logical_not應用基本類似.void test_logical_and(){bool foo[] = {true, false, true, false};bool bar[] = {true, true, false, false};bool result[4];transform(foo, foo+4, bar, result, std::logical_and<bool>());std::cout << std::boolalpha << "Logical AND:\n";for (int i = 0; i < 4; ++i)std::cout << foo[i] << " AND " << bar[i] << " = " << result[i] << std::endl;}