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

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

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