std::map Custom Comparator optimization guide as Expected with std::string in C++20
Can someone help me understand I'm working on a project and hit a roadblock... I'm upgrading from an older version and I've been researching this but I tried several approaches but none seem to work... I've been banging my head against this for hours. Quick question that's been bugging me - I'm working with an scenario where my custom comparator for a `std::map` isn't behaving as I anticipated when using `std::string` keys... I want to create a case-insensitive map, but it seems that the comparator isn't applied correctly. Here's the code snippet I'm using: ```cpp #include <iostream> #include <map> #include <string> #include <algorithm> struct CaseInsensitiveCompare { bool operator()(const std::string& a, const std::string& b) const { return std::lexicographical_compare(a.begin(), a.end(), b.begin(), b.end(), [](char c1, char c2) { return std::tolower(c1) < std::tolower(c2); }); } }; int main() { std::map<std::string, int, CaseInsensitiveCompare> myMap; myMap["Apple"] = 1; myMap["banana"] = 2; myMap["Cherry"] = 3; for (const auto& pair : myMap) { std::cout << pair.first << " : " << pair.second << '\n'; } return 0; } ``` When I run this code, I expect the output to show the keys sorted in a case-insensitive manner, but I'm getting: ``` Apple : 1 Cherry : 3 banana : 2 ``` The expected output should have been: ``` Apple : 1 banana : 2 Cherry : 3 ``` I've ensured that the `CaseInsensitiveCompare` is correctly passed as the third template argument to `std::map`. However, it seems that the default `std::string` comparison is overriding my custom comparator. I've tried debugging it and even checked if my comparator is being called, but it appears not to be the case. Am I missing something in the setup of the comparator, or is there a specific behavior in C++20 that I need to be aware of? Any insights would be greatly appreciated! This is part of a larger web app I'm building. For context: I'm using Cpp on Ubuntu. Is there a better approach? I'm working on a CLI tool that needs to handle this. Any help would be greatly appreciated! I've been using Cpp for about a year now. This is happening in both development and production on Linux. What would be the recommended way to handle this? I've been using Cpp for about a year now. Has anyone dealt with something similar?