#include <vector>
#include <numeric>
#include <algorithm>
#include <iterator>
#include <iostream>
#include <functional>
std::vector<int> v(10, 2);
std::partial_sum(v.cbegin(), v.cend(), v.begin());
std::cout << "Among the numbers: ";
std::copy(v.cbegin(), v.cend(), std::ostream_iterator<int>(std::cout, " "));
std::cout << '\n';
// minden elemre igaz e
if (std::all_of(v.cbegin(), v.cend(), [](int i){ return i % 2 == 0; })) {
std::cout << "All numbers are even\n";
}
// egyikre sem igaz (mivel a modulus a remindert szamolja es az mindenhol nulla azaz mindenhol hamissa konvertalodik)
if (std::none_of(v.cbegin(), v.cend(), std::bind(std::modulus<int>(), std::placeholders::_1, 2))) {
std::cout << "None of them are odd\n";
}
struct DivisibleBy {
const int d;
DivisibleBy(int n) : d(n) {}
bool operator()(int n) const { return n % d == 0; }
};
// barmelyik elemre a range en belul igaz e
if (std::any_of(v.cbegin(), v.cend(), DivisibleBy(7))) {
std::cout << "At least one number is divisible by 7\n";
}
void goodbye(const std::string& s) {
std::cout << "Goodbye " << s << '\n';
}
class Object {
public:
void hello(const std::string& s) {
std::cout << "Hello " << s << '\n';
}
};
// fvpointer void visszateresi ertekkel es const string& parameterrel
typedef std::function<void(const std::string&)> ExampleFunction;
Object instance;
std::string str("World");
ExampleFunction f = std::bind(&Object::hello, &instance, std::placeholders::_1);
// equivalent to instance.hello(str)
// az str a placeholder
f(str);
f = std::bind(&goodbye, std::placeholders::_1);
// equivalent to goodbye(str)
f(str);
struct Sum {
Sum(): sum{0} { }
void operator()(int n) { sum += n; }
int sum;
};
std::vector<int> nums{3, 4, 2, 8, 15, 267};
auto print = [](const int& n) { std::cout << " " << n; };
std::cout << "before:";
std::for_each(nums.begin(), nums.end(), print);
std::cout << '\n';
std::for_each(nums.begin(), nums.end(), [](int &n){ n++; });
// calls Sum::operator() for each number
Sum s = std::for_each(nums.begin(), nums.end(), Sum());
std::cout << "after: ";
std::for_each(nums.begin(), nums.end(), print);
std::cout << '\n';
std::cout << "sum: " << s.sum << '\n';
std::vector<int> v2{ 1, 2, 3, 4, 4, 3, 7, 8, 9, 10 };
// determine how many integers in a std::vector match a target value.
int target1 = 3;
int target2 = 5;
int num_items1 = std::count(v2.begin(), v2.end(), target1);
int num_items2 = std::count(v2.begin(), v2.end(), target2);
std::cout << "number: " << target1 << " count: " << num_items1 << '\n';
std::cout << "number: " << target2 << " count: " << num_items2 << '\n';
// use a lambda expression to count elements divisible by 3.
int num_items3 = std::count_if(v2.begin(), v2.end(), [](int i){return i % 3 == 0;});
std::cout << "number divisible by three: " << num_items3 << '\n';
bool IsOdd (int i) {
return ((i%2)==1);
}
int n1 = 3;
int n2 = 5;
std::vector<int> v3{0, 1, 2, 3, 4};
auto result1 = std::find(std::begin(v3), std::end(v3), n1);
auto result2 = std::find(std::begin(v3), std::end(v3), n2);
if (result1 != std::end(v3)) {
std::cout << "v contains: " << n1 << '\n';
} else {
std::cout << "v does not contain: " << n1 << '\n';
}
if (result2 != std::end(v3)) {
std::cout << "v contains: " << n2 << '\n';
} else {
std::cout << "v does not contain: " << n2 << '\n';
}
std::vector<int> myvector;
myvector.push_back(10);
myvector.push_back(25);
myvector.push_back(40);
myvector.push_back(55);
std::vector<int>::iterator it = std::find_if (myvector.begin(), myvector.end(), IsOdd);
std::cout << "The first odd value is " << *it << '\n';
//////copy
std::vector<int> from_vector(10);
std::iota(from_vector.begin(), from_vector.end(), 0);
std::copy(from_vector.begin(), from_vector.end(), std::ostream_iterator<int>(std::cout, " "));
std::cout << '\n';
std::vector<int> to_vector;
std::copy(from_vector.begin(), from_vector.end(), std::back_inserter(to_vector));
std::cout << "to_vector contains: ";
std::copy(to_vector.begin(), to_vector.end(), std::ostream_iterator<int>(std::cout, " "));
std::cout << '\n';
//////copy_n
std::string in = "1234567890";
std::string out;
std::copy_n(in.begin(), 4, std::back_inserter(out));
std::cout << out << '\n';
/////////////////////////////////////////////////////////
///////copy_if
std::vector<int> foo = {25,15,5,-5,-15};
std::vector<int> bar (foo.size());
// copy only positive numbers:
auto it2 = std::copy_if (foo.begin(), foo.end(), bar.begin(), [](int i){return !(i<0);} );
bar.resize(std::distance(bar.begin(),it2)); // shrink container to new size
std::cout << "bar contains:";
for (int& x: bar) std::cout << ' ' << x;
std::cout << '\n';