STL and User-Defined Classes

Question:
I’m new to the Standard Template Library. How do I incorporate a user-defined class into a hash_map? What functions do I need to overload? I get compiler errors when I try to insert into my hash_map for even the simplest of classes.

Answer:
Hash_map is not part of the Standard Template Library, at least officially. Hashed containers were presented to the C++ standardization committee too late, so the committee did not have sufficient time to include them in the C++ Standard.

Nevertheless, several vendors now offer proprietary hashed containers as an extension to Standard. However, these extensions are not compatible, nor is there any guarantee that they will be standardized in the future.

You didn’t post the code that causes compilation errors or the error messages that you received, so I cannot give a specific answer. However, you should check the interaction of namespaces and the hash_map (i.e., is hash_map defined in the namespace STD or perhaps another namespace?).

In addition, make sure that your classes define appropriate default ctor, copy ctor, assignment operator, and destructor. Failing to do so is the most fertile source of compilation errors when using STL containers.

Share the Post:
Share on facebook
Share on twitter
Share on linkedin

Overview

The Latest

Top 5 B2B SaaS Marketing Agencies for 2023

In recent years, the software-as-a-service (SaaS) sector has experienced exponential growth as more and more companies choose cloud-based solutions. Any SaaS company hoping to stay ahead of the curve in this quickly changing industry needs to invest in effective marketing. So selecting the best marketing agency can mean the difference

technology leadership

Why the World Needs More Technology Leadership

As a fact, technology has touched every single aspect of our lives. And there are some technology giants in today’s world which have been frequently opined to have a strong influence on recent overall technological influence. Moreover, those tech giants have popular technology leaders leading the companies toward achieving greatness.

iOS app development

The Future of iOS App Development: Trends to Watch

When it launched in 2008, the Apple App Store only had 500 apps available. By the first quarter of 2022, the store had about 2.18 million iOS-exclusive apps. Average monthly app releases for the platform reached 34,000 in the first half of 2022, indicating rapid growth in iOS app development.