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Exercises
Basic facilities


2.1   String functions  

Continue the programming from above with a C++ program that uses the find, replace, substr, and size functions from The C++ Programming Language section 20.3.11 - 20.3.14.
 


2.2   Another example/exercise with C++ references  

On the accompanying slide we have shown a number of examples that illustrate different uses of reference types in C++.

Your task in this exercise is to come up with yet another good and convincing example of reference types in C++. (Please use your own fantasy - not some internet fantasy).

Your program can be seen as the solution to a programming exercise about references. Please provide a short formulation of this exercise.

 


2.3   Pointers in combination with references  

In this exercise we will explore pointers and references relative to each other. Play and learn! We do this in context of a function that returns the maximum of two doubles. Here is the function with call-by-value parameters:

  double max(double a, double b){
    return a < b ? b : a;
  }

In all cases below, program the max function, call it, make make sure you get the expected result from the call.

  1. As a warm up: Make a version with call by const references instead of call by value parameters.
  2. Demonstrate that pointers to references do not exist.
  3. Make a version with references to pointers. Does that make sense to you?
  4. Next, make version with const references to pointers.
  5. Finally, a version with const references to pointers to double constants

Can you imagine other interesting variations?

 

Solution


2.4   Ways of returning results from the div function  

This exercise works in the context of the divide program from the slide about constant references.

Program the struct ldiv_t and the function div yourself, instead of using the definitions from the std namespace.

Run the program with your own versions of ldiv_t and div.

Experiment with returning a reference ldiv_t& from div. (See page 282-283 in The C++ Programming Language).

And similarly, experiment with returning a const reference const ldiv_t& from the div.

 

Solution


2.5   Understand Vectors  

Take a look at the documentation of the (template) class vector at www.cplusplus.com

Familiarize yourself with the vector member functions, and read some of the (numerous) small examples which are available

 


2.6   Use of class Point in C++  

In this exercises we will explore some basic similarities and differences between use of classes in Java/C# and C++. (In the scope of this lecture we will NOT be concerned with class definition details. This belongs to the next lecture). In particular we will study creation/allocation of objects, and parameter passing of objects to a function/method.

The starting point is the simple Point class in C# and a sample C# client program that creates and operates on points. Make sure that you familiarize yourself with the correct output of this program. Predict it before you run it.

We provide a similar Point class in C++. The C++ definitions of the Point functions are also provided (but they are not important for this exercise). You are supposed to explore various uses of class Point in C++.

  1. Write a C++ client program that corresponds as close as possible to the C# client program. In this version of the C++ program you should access Point objects via pointers. First, write a version where you allocate the points in the free store.
  2. Adjust the C++ program from above such that the points are allocated on the stack, with pointers established to these (by use of the address operator).
  3. Write another version of the C++ client program uses C++ references instead of pointers. The goal is to come as close as possible to the pointer-based program you wrote above.
  4. Finally, write a C++ client program that use pure and simple value semantics of points. In other words, do not use references nor pointers at all in this version of the C++ program. We accept that the meaning of the program changes due to the introduction of value semantics. Predict the output of the program before you run it.

Feel free to do other experiments based on the Point classes that help you understand the similarities and differences between use of C# and C++ classes, pointers, references, and stack allocation of C++ objects.

 

Solution


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