Lab 13: templates, pair, and vector

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Exercise 1. swap box

I’ve placed a file SwapBox.hh in this repo. This the start of the definition of a template class SwapBox<T> that keeps track of a pair of values of type T. It has a get method that always returns the first component of that pair, and a set method that allows a client to set only the first value of the pair. Finally, it has a method swap that swaps the two elements in that pair.

I’ve only given the class definition in this file, but I haven’t written any of the method definitions. Write those. (Recall that, because this is a template class, they need to be written within the .hh file.) You can use the file Stck_T.hh as a guide to the template method syntax.

The contents of a SwapBox<T> object is a std::pair<T,T> object as defined in the C++ STL. It has two components, a first of type T and a second of type T.

I’ve also written code for a client that can be compiled with the line

g++ -std=c++11 -o swap_int swap_int.cc

It builds an object and tests each of the methods.

Write a similar client swap_string.cc that tests a SwapBox<std::string> object.

Exercise 2. odometer

I’ve included the definition of a Odometer class in a file Odometer.hh. This defines an odometer object that is a vector of digits between 0 and base-1. And odometer can be reset which sets all of its digits to 0. It can be incremented, and that bumps the odometer up by one. Below is a use of this class in the client odom.cc:

% ./odom                                    
Enter the width of your odometer: 3
Enter its base: 2
How many times would you like to advance it?
10
Okay. Here goes...
000
001
010
011
100
101
110
111
000
001
010

Here we have a binary odometer with three bits. And then we increment it 10 times starting at 000. After eight “ticks” the odometer wraps around to all 0s.

In a file named Odometer.cc write each of the methods for this odometer class. Since we use a std::vector<int> to represent the odometer, you might find these features of vector useful:

• vector<T>(void): this constructor builds a vector of size 0.
• resize(int sz): this sets a vector to a certain size.
• size(void): this gives the number of components of the vector.
• at(int i): this accesses the i-th component of the vector.
• for (int x: v) ... : you can iterate over the elements x of a std::vector<int> v.