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1. What does this program print? ``

cpp
#include <algorithm>
#include <iostream>
#include <vector>

int main() {
    std::vector<int> v{59, 60, 61, 100, 0};
    int n = std::count_if(v.begin(), v.end(), [](int s) { return s >= 60; });
    std::cout << n << '\n';
}

``

2431

2. What does this program print? ``

cpp
#include <iostream>

int main() {
    int n = 10;
    auto f = [n](int k) mutable { n += k; return n; };
    f(1);
    std::cout << f(2) << ' ' << n << '\n';
}

``

13 1012 1013 1311 10

3. What does this program print? ``

cpp
#include <iostream>

class Account {
public:
    inline static int opened = 0;
    explicit Account(int cents) : cents_(cents) { ++opened; }
    static Account withBonus(int cents) { return Account(cents + 500); }
    int cents() const { return cents_; }
private:
    int cents_;
};

int main() {
    Account a(100);
    Account b = Account::withBonus(250);
    std::cout << b.cents() << ' ' << Account::opened << '\n';
}

``

250 1750 1250 2750 2

4. What does the static keyword mean on a member function such as static Account withBonus(int cents)?

Each object gets its own copy of the functionThe function belongs to the class and has no this pointerThe function runs only once and remembers its resultThe function can be called only from main

5. In auto addToTotal = [&total](int n) { total += n; };, what does &total mean?

The lambda keeps a copy of total, made once when the lambda is createdThe lambda cannot read total, only write to itThe lambda refers to the real total, so each call changes the variable outside the lambdaThe lambda is marked mutable, so it can change its own copy

Static and lambdas