Understanding Binary Operators in C++: A Deep Dive

Binary operators are the bread and butter of many programming tasks, especially in C++. But ever found yourself scratching your head over what they must return when their job is to produce a new value? Let’s clear up the confusion and master this concept together!

First off, what exactly are binary operators? These are functions that require two operands and return a result based on a specific operation. Think of them like chefs combining two ingredients to create a new dish. Essential, right? Now, let’s get into the nitty-gritty of their return values and why it's crucial to understand them for your C++ programming journey.

When we look closely, the answer to what binary operators must return are constant objects by value. You might be thinking, “Dust off my memory – was that always the case?” It most certainly is! But let’s break down why the other options just won’t cut it.

Option A – A New Modified Object by Reference:
At first glance, this seems almost plausible. After all, when you’re modifying something, don’t you want to reference that change? However, when it comes to binary operators, they primarily deal with values, not references. So, while they work with the data, they don’t spit back a reference to that data. Think of it as getting a takeout box — you get the food (the value) but not the ingredients list (the reference).

Option C – Void:
Now, this option makes you think! Void implies zero return. But in our case, we want a return value representing the results of the operation. Just like you wouldn't cook a meal if you're not going to serve it, a binary operator must serve up something! So nope, void’s not the winner here either.

Option D – A Non-const Reference to the Modified Object:
It may sound fancy, but we're still left with the same conclusion. Binary operators function within a framework that requires a return value — not a non-constant reference of what they did. It’s like being asked for a receipt after buying groceries; you want proof of what transaction occurred, not a reference to why you bought those cookies!

Now we can confidently conclude that the only absolutely correct option is indeed Option B – A constant object by value.

Don’t you love how resolution in programming gives you a sense of achievement? Preparing for comprehensive quizzes from foundational texts like 'Thinking in C++' solidifies these concepts and not only tests your knowledge but brings hope that mastery is right around the corner.

If you’re gearing up for a quiz, don’t just memorize — engage! Understanding why these choices are made — kind of like choosing between cake or pie — deepens your comprehension and equips you for complex scenarios.

So, next time you tackle binary operators in your C++ projects, remember: it’s all about that return value! Every time you engage in such binary operations, know it’s shaping your knowledge and skills, much like the ingredients in that perfect dish you aim to cook. Happy coding!