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1. What does this program print? Words are separated by single spaces. ``

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

int main() {
    std::vector<std::string> v = {"pear", "Peach", "apple", "Apple", "10", "9"};
    std::ranges::sort(v);
    for (const auto& s : v) std::cout << s << " ";
    std::cout << "\n";
}

``

9 10 Apple Peach apple pear10 9 apple Apple Peach pear10 9 Apple Peach apple pearApple 10 9 Peach apple pear

2. What does this program print? Words are separated by single spaces. ``

cpp
#include <algorithm>
#include <cctype>
#include <iostream>
#include <ranges>
#include <string>
#include <vector>

bool ci_less(const std::string& a, const std::string& b) {
    return std::ranges::lexicographical_compare(a, b, {},
        [](char c) { return std::tolower(static_cast<unsigned char>(c)); },
        [](char c) { return std::tolower(static_cast<unsigned char>(c)); });
}

int main() {
    std::vector<std::string> v = {"Cat", "dog", "cat", "CAT", "Bird"};
    std::ranges::stable_sort(v, ci_less);
    for (const auto& s : v) std::cout << s << " ";
    std::cout << "\n";
}

``

Bird Cat cat CAT dogBird cat Cat CAT dogBird CAT Cat cat dogCat cat CAT Bird dog

3. True or false: std::ranges::sort guarantees to keep equal items in their input order, so Apple stays before apple after a case-insensitive sort.

True, because sort always keeps equal items in their input orderFalse, because sort makes no promise about the order of equal items, so std::ranges::stable_sort is needed

4. True or false: std::string("apple") < std::string("apples") is true.

True, because apple runs out of letters first, so it comes firstFalse, because apples has more letters, so it comes first

5. Why does a plain std::ranges::sort put Zebra before apple?

Zebra is longer than apple, and longer words come firstThe sort compares the words in reverse alphabetical orderThe sort skips the first letter of each word before it comparesZ has code 90 and a has code 97, so the capital letter comes first

Ordering