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Chapter 17: Problem 7

Give the definition for the member function get_element for the class template Pair discussed in the section "Syntax for Class Templates."

Short Answer

Expert verified
Answer: The `get_element` function of a Pair class template returns the value of a specified data member (either `first` or `second`) of a Pair object based on the input index parameter. The function handles different data types by defining the class as a template and using the `T` placeholder to represent any data type. The `get_element` function uses the same `T` placeholder for the data members and the return type of the function, ensuring that it can handle any data type specified when creating a Pair object.

Step by step solution

01

Understand the Pair class template and its syntax

Before defining the `get_element` function, let's first understand the Pair class template and its syntax. A class template helps in creating a generic class that can work with different data types. The basic structure of the Pair class template can be shown as: ```cpp template class Pair { public: void setValues(T a, T b); T get_element(int index); private: T first; T second; }; ``` Here, `T` is the placeholder to represent any data type. The class contains two data members `first` and `second`, and `setValues` is a member function to set the values of these two data members.
02

Define the get_element function

Now, we will define the `get_element` function. The purpose of this function is to return the value of the specified data member (either `first` or `second`) of the Pair object. We will achieve this using an input parameter `index` which will be an integer value – 1 for the first element and 2 for the second element. To demonstrate the template functionality, we will provide the implementation inside the class definition itself. Here's the implementation of `get_element` function: ```cpp template class Pair { public: void setValues(T a, T b) { first = a; second = b; } T get_element(int index) { if (index == 1) { return first; } else if (index == 2) { return second; } // Add an error message or exception handling if the index is invalid } private: T first; T second; }; ``` This `get_element` function checks the value of the `index` and returns the corresponding data member's value.

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Most popular questions from this chapter

In the template prefix template \(\) what kind of variable is the parameter \(T\) ? a. \(T\) must be a class. b. \(T\) must not be a class. \(c\), \(T\) can be only types built into the \(C++\) language. d. \(T\) can be any type, whether built into \(C++\) or defined by the programmer.

We have used three kinds of absolute value function: abs, labs, and fabs. These functions differ only in the type of their argument. It might be better to have a function template for the absolute value function. Give a function template for an absolute value function called absolute. The template will apply only to types for which \(<\) is defined, for which the unary negation operator is defined, and for which the constant \(\theta\) can be used in a comparison with a value of that type. Thus, the function absolute can be called with any of the number types, such as int, long, and double. Give both the function declaration and the function definition for the template.

Write a function template named maximum. The function takes two values of the same type as its arguments and retums the larger of the two arguments (or either value if they are equal). Give both the function declaration and the function definition for the template. You will use the operator \(<\) in your definition. Therefore, this function template will apply only to types for which \(<\) is defined. Write a comment for the function declaration that explains this restriction.

Give the definition of a template class called HeterogeneousPair that is like the class template Pair discussed in the section "Syntax for Class Templates," except that with HeterogeneousPair the first and second positions may store values of different types. Use two type parameters T1 and \(\mathrm{T} 2 ;\) all items in the first position will be of type \(\mathrm{T} 1\), and all items in the second position will be of type \(T 2 .\) The single mutator method set_element in the template class Pair should be replaced by two mutator methods called set_first and set_second in the template class HeterogeneousPair, Similarly, the single accessor method get_element in the template class Pair should be replaced by two accessor methods called get_first and get_second in the template class HeterogeneousPair.

Display 7.10 shows a function called search, which searches an array for a specified integer. Give a function template version of search that can be used to search an array of elements of any type. Give both the function declaration and the function definition for the template. Hint: It is almost identical to the function given in Display 7.10
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