👀 Views: 64 💬 Answers: 1 📅 Created: 2025-06-12

cpp std-sort std-vector custom-comparator

I'm attempting to set up I'm migrating some code and I tried several approaches but none seem to work..... After trying multiple solutions online, I still can't figure this out. I'm working with unexpected behavior when using `std::sort` on a `std::vector` of custom objects in C++. I have a simple class `Person` with a name and age, and I'm trying to sort a vector of these objects by their age using a custom comparator. However, after sorting, the order of the elements does not match what I expected. Here’s the code I’m working with: ```cpp #include <iostream> #include <vector> #include <algorithm> class Person { public: std::string name; int age; Person(std::string n, int a) : name(n), age(a) {} }; bool compareByAge(const Person& a, const Person& b) { return a.age < b.age; } int main() { std::vector<Person> people = { Person("Alice", 30), Person("Bob", 25), Person("Charlie", 35) }; std::sort(people.begin(), people.end(), compareByAge); for (const auto& person : people) { std::cout << person.name << " " << person.age << '\n'; } return 0; } ``` I expected the output to be sorted by age in ascending order, but I see the following output instead: ``` Alice 30 Bob 25 Charlie 35 ``` It seems that the `std::sort` function is not working as intended. I’ve checked that the comparator function is correctly implemented and returns a boolean value as expected. I also verified that the `std::vector` is initialized correctly. I've even tried using a lambda function instead of the `compareByAge` function directly, but the results are still incorrect. Could this be an scenario related to the way `std::sort` interacts with the custom comparator, or is there something I'm missing regarding the logic in my implementation? Any insights would be greatly appreciated! This is part of a larger service I'm building. Any help would be greatly appreciated! I'm working on a application that needs to handle this. How would you solve this? I'm coming from a different tech stack and learning Cpp. I'm open to any suggestions. Could this be a known issue? My team is using Cpp for this web app. What are your experiences with this? Any suggestions would be helpful.