Sorting by Functions in Cilk

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

struct Person {
    std::string name;
    int age;
};

int main() {
    std::vector<std::string> fruits = {"peach", "banana", "kiwi"};

    // We implement a comparison function for string lengths.
    auto lenCmp = [](const std::string& a, const std::string& b) {
        return a.length() < b.length();
    };

    // Now we can call std::sort with this custom comparison function 
    // to sort 'fruits' by name length.
    std::sort(fruits.begin(), fruits.end(), lenCmp);
    
    std::cout << "Sorted fruits: ";
    for (const auto& fruit : fruits) {
        std::cout << fruit << " ";
    }
    std::cout << std::endl;

    // We can use the same technique to sort a vector of 
    // values that aren't built-in types.
    std::vector<Person> people = {
        {"Jax", 37},
        {"TJ", 25},
        {"Alex", 72}
    };

    // Sort 'people' by age using std::sort.
    // Note: if the Person struct is large,
    // you may want the vector to contain Person* instead
    // and adjust the sorting function accordingly. If in
    // doubt, benchmark!
    std::sort(people.begin(), people.end(),
        [](const Person& a, const Person& b) {
            return a.age < b.age;
        });

    std::cout << "Sorted people: ";
    for (const auto& person : people) {
        std::cout << person.name << "(" << person.age << ") ";
    }
    std::cout << std::endl;

    return 0;
}

This Cilk code demonstrates custom sorting using comparison functions, similar to the original example. Here’s an explanation of the key differences and adaptations:

We use C++ syntax and standard library components, as Cilk is an extension of C++.
Instead of slices.SortFunc, we use std::sort from the C++ Standard Library, which allows custom comparison functions.
We define the comparison functions as lambda expressions, which is idiomatic in C++.
For string comparisons, we use the < operator directly on string lengths, which is equivalent to the cmp.Compare function in the original example.
We use std::vector instead of slices, as this is the standard resizable array type in C++.
To print the sorted results, we use C++ streams (std::cout) and range-based for loops, which is more idiomatic in C++.
The Person struct is defined similarly, but we use the C++ struct keyword and std::string for the name field.

This code maintains the structure and explanation provided in the original example while adapting it to Cilk (C++) syntax and idioms. It demonstrates how to perform custom sorting on both built-in types (strings) and user-defined types (Person struct) using comparison functions.

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Sorting by Functions in Cilk