62 lines
3.5 KiB
Markdown
62 lines
3.5 KiB
Markdown
[](https://classroom.github.com/a/30SwKKx2)
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## IF.03.22 Procedural Programming
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# Assignment Pointer Fun
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## Objective
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This assignment lets you practise a bit more with the difference between references and values.
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## Materials
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- Atom or any other editor
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- gcc
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- terminal.
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## Required Tasks
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1. Create a file called `pointer_func.c` and write a `main` function which declares
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- an integer variable `int_value`
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- a pointer to an integer `int_pointer`
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3. 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.
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2. Define a function `print_integers` which accepts the following paramters
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- an integer variable `int_value`
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- a pointer to an integer `int_pointer`
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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
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`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.
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4. Call the function `print_integers` in the `main` function and test your implementation.
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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.
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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.
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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`.
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| Declaration/Usage | Scenario | Syntax Example | Description of the Example
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| --- | --- |--- | --- |
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| Declaration | Declaration of a value | `int x` | A variable of type `int` is declared. This variable can hold an integer value |
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| Declaration | | | |
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| Usage | Using a value | `foo(x)` | The function `foo()` is called and the value of a variable `x` is passed to it |
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| Usage | | | |
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| Usage | | | |
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## Hints
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- Take care to keep the work loop "Implement a little", "Test a little" to avoid the 100 lines of error mess.
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## Extra Credit
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Document your implementation in an extra text file or in an inline comment. In particular:
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- Write down the reasons, how you assigned values to the variables in the main function.
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- Give alternatives how to pass parameters when calling the different functions.
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- Write down the reasons, why some variables are not changed by `change_integers`.
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## Evaluation
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All coding assignments will get checked. Most common reasons that your assignment is marked down are:
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- Program does not build or builds with warnings
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- One or more items in the *Required Tasks* section are not satisfied
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- Submitted code is visually sloppy and hard to read
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## Things to Learn
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- Repeat using primitive data types, like integer, float/doubles
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- Repeat implementing functions
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- Repeat pointer handling on primitive data types
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