IF.03.22 Procedural Programming

Assignment Pointer Fun

Objective

This assignment lets you practise a bit more with the difference between references and values.

Materials

• Atom or any other editor
• gcc
• terminal.

Required Tasks

1. Create a file called pointer_func.c and write a main function which declares

   • an integer variable int_value
   • a pointer to an integer int_pointer

2. Assign some values to the variables. Take care how to assign a value to the pointer. What is possible there? Describe this briefly in a comment right after this line of code.

3. Define a function print_integers which accepts the following paramters

   • an integer variable int_value
   • a pointer to an integer int_pointer

   The function shall print the values (note, also the value at the address which is stored in int_pointer) of both parameters in the following form Got an integer value <x> and an address to an integer with value <y> where <x> and <y> shall be replaced by the actual values of the parameters passed.

4. Call the function print_integers in the main function and test your implementation.

5. Define a function change_integers which accepts the same parameters as print_integers. In the function body the values of the two parameters shall be changed to some different values.

6. Call the function change_integers and then again call print_integers at the end of the main function. Which values are changed, which are not? Why? Describe this briefly in a comment right after the call of the functions.

7. Describe the five scenarios which can occur when declaring and using variables (declare a value, declare a pointer, get the value, get the value of a pointer, get the pointer of a value). Make a table as follows (two scenarios are already filled out for you to give you a more precise picture what to be done here). Write this table by hand, scan it (or take a photo) and add it to your repository. The name of the file shall be scenarios.jpg or scenarios.png.

Declaration/Usage	Scenario	Syntax Example	Description of the Example
Declaration	Declaration of a value	int x	A variable of type int is declared. This variable can hold an integer value
Declaration
Usage	Using a value	foo(x)	The function foo() is called and the value of a variable x is passed to it
Usage
Usage

Hints

• Take care to keep the work loop "Implement a little", "Test a little" to avoid the 100 lines of error mess.

Extra Credit

Document your implementation in an extra text file or in an inline comment. In particular:

• Write down the reasons, how you assigned values to the variables in the main function.
• Give alternatives how to pass parameters when calling the different functions.
• Write down the reasons, why some variables are not changed by change_integers.

Evaluation

All coding assignments will get checked. Most common reasons that your assignment is marked down are:

• Program does not build or builds with warnings
• One or more items in the Required Tasks section are not satisfied
• Submitted code is visually sloppy and hard to read

Things to Learn

• Repeat using primitive data types, like integer, float/doubles
• Repeat implementing functions
• Repeat pointer handling on primitive data types