Question

Mark the following statements as true or false. a. In C++, all operators can be overloaded for user-defined data types. b. In C++, operators cannot be redefined for built-in types. c. The function that overloads an operator is called the operator function. d. C++ allows users to create their own operators. e. The precedence of an operator cannot be changed, but its associativity can be changed. f. Every instance of an overloaded function has the same number of parameters. g. It is not necessary to overload relational operators for classes that have only int member variables. h. The member function of a class template is a function template. i. When writing the definition of a friend function, the keyword friend must appear in the function heading. j. Templates provide the capability for software reuse. k. The function heading of the operator function to overload the preincrement operator (++) and the post-increment operator (++) is the same because both operators have the same symbols.

Short answer

a. False, b. True, c. True, d. False, e. False, f. False, g. False, h. True, i. False, j. True, k. False.

Step-by-step solution

Analyze Statement a

In C++, not all operators can be overloaded. Operators like the scope (``::``), member access (``.``), and the conditional operator (``?:``) cannot be overloaded. Therefore, this statement is false.

Analyze Statement b

In C++, built-in types already have their operators defined, and these definitions cannot be changed or redefined. Thus, this statement is true.

Analyze Statement c

An operator function is a special function that overloads an operator to work with user-defined data types in C++. Hence, this statement is true.

Analyze Statement d

In C++, users cannot create new operators, only overload existing ones for user-defined data types. Therefore, this statement is false.

Analyze Statement e

In C++, neither the precedence nor the associativity of operators can be changed by overloading. Therefore, this statement is false.

Analyze Statement f

Overloaded functions, including operator functions, can have a different number of parameters, as long as their parameters match the required operator's syntax. Thus, this statement is false.

Analyze Statement g

Overloading relational operators in classes with only int member variables can still be useful if those ints represent some abstract entity where relational operations are meaningful. Therefore, it is sometimes necessary, making this statement false.

Analyze Statement h

The member function of a class template can indeed be a function template. Therefore, this statement is true.

Analyze Statement i

When defining a friend function outside of a class in C++, the keyword `friend` does not appear in the function definition; it's only in the class declaration. Hence, this statement is false.

Analyze Statement j

Templates are designed to enable software reuse, allowing the same code to work with different data types. So, this statement is true.

Analyze Statement k

The operator functions for pre-increment and post-increment operators differ in their parameter list; the post-increment version takes an additional dummy int parameter. Therefore, this statement is false.

Key concepts

C++ Templates

C++ templates are a powerful feature in C++ that allow developers to write generic and flexible code. Templates enable you to create a single function or class to work with different data types without rewriting code for each type. This way, you can significantly increase code reusability and efficiency.

There are two main types of templates in C++:

• **Function Templates**: Used to create functions that can operate on different data types. For example, a function template for adding two numbers would work for both integers and floats without any change to the code.
• **Class Templates**: Used to create classes that can handle any data type. A common example is the `std::vector`, a dynamic array that can store items of any type.

Templates are declared with the `template` keyword, followed by template parameters inside angle brackets. These parameters act as placeholders for the types you want to work with. This feature of C++ makes it extremely robust for building scalable applications.

Friend Functions in C++

Friend functions in C++ are special functions that are allowed to access private and protected members of a class. These are not member functions but have been "invited" into the private circle of a class through the `friend` keyword.

They're often used when two or more classes need to work closely together. By declaring a function as a friend, a class gives it access rights to its non-public members, enabling a tighter coordination. For example, if you have closely related classes where one needs to modify the private data of another, a friend function can be very helpful.

When you're defining a friend function inside the class header, you'll use the `friend` keyword, followed by the full function declaration. However, remember that any such function defined outside the class scope does not include the `friend` keyword—a common source of confusion for newcomers.

Relational Operators Overloading

In C++, you can overload relational operators such as `<`, `>`, `<=`, `>=`, `==`, and `!=` to work with user-defined data types. This operator overloading allows objects of a class to be compared using these operators as naturally as primitive data types.

Operator overloading is done by defining a function for the operator keyword. For example, to overload the `==` operator, you would define a function with the signature `bool operator==(const ClassName &obj)`. This function will provide the logic to compare the invoking object (`*this`) with the object passed as a parameter.

Overloading relational operators is especially useful when developing classes where such comparisons are meaningful. Despite potentially consisting of only basic data types like `int` variables, custom comparison logic might still be needed based on the context or semantics.

Precedence and Associativity in C++

In C++, operator precedence and associativity determine the order of evaluation in expressions that involve more than one operator. Precedence specifies which operator should be evaluated first. Associativity determines the order in which operators of the same precedence level are evaluated, from left to right or right to left.

This is crucial because it can dramatically change the meaning of expressions. For example, in the expression `a + b * c`, multiplication has a higher precedence than addition, so `b * c` is evaluated first.

It's important to note that when you overload operators in C++, you cannot change their precedence or associativity. They remain as defined by the C++ language. Therefore, when overloading, you must ensure that the operation is intuitive and respects the natural precedence and associativity expected by other programmers.