auto and Range-based for

Writing Less, Saying More

auto x = 42;         // int
auto y = 3.14;       // double
auto s = string("hi"); // string

// Especially useful with complex types:
map<string, vector<int>>::iterator it = data.begin(); // old way
auto it = data.begin();                                  // new way!

Range-based for

vector<int> nums = {1,2,3,4,5};

for (int x : nums)          cout << x;   // by value (copy)
for (const int& x : nums)  cout << x;   // by const ref (cheap)
for (int& x : nums)        x *= 2;      // by ref (modifies)

Structured bindings (C++17)

map<string,int> scores = {{"Alice",95},{"Bob",87}};
for (auto& [name, score] : scores) {
    cout << name << ": " << score;
}

Your Task

Write filterPositive(vector<int> v) using range-based for that returns only elements > 0.