Lab 1: Linux and C++ Revision

# Lab 1

## Linux and C++ Revision

##### Presentation by *Asem Alaa*

<div class="my-header"><img src="/gallery/cairo.png" style="height: 30px;" /></div>
<div class="my-footer"><span>SBE201 Data Structures and Algorithms  (Spring 2020) - By <em>Asem Alaa</em></span></div>

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## Linux Spaces
### System-wise space vs. User space

* When working on your projects, you are a **USER**.
* When installing/upgrading system-wise application/library, you are an **ADMIN**.

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## Jumping between folders (changing directories)

```terminal
$ cd (Relative Path|Absolute Path)
```

* In terminal commands, with `A|B`, I mean "Either A or B".

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## Listing files in the current directory (folder)

### List files/directories inside the current directory of the terminal
```terminal
$ ls 
```

### List files/directories on from other directory
```terminal
$ ls (Relative Path|Relative Path)
```

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## Change folder name or moving folder name

```terminal
$ mv (file|directory) (new file|new directory)
```

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## Copy file

```terminal 
$ cp (file) (target path)
```

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## Copy directory

```terminal
$ cp -r (directory) (target path)
```

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## Create a new directory (folder)

```terminal
$ mkdir (new folder name)
```

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## Removing a file

```terminal
$ rm (file)
```

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## Remove a directory

```terminal
$ rm -r (directory)
```

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## WARNING: Did you say `rm`?

### HOW ABOUT `sudo rm -rf /`

DO NOT DO THIS!
```terminal
$ sudo rm -rf /
```

--
<img style="width:80%" src="/gallery/delete.webp" />

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## Updating & Upgrading your Linux

Upgrades are very important. Many hardware drivers issues are being fixed through these updates. Also, security-wise,
updates guarantees your system to be safe against hackable vulnerabilities. For example, *Spectre* and *Meltdown* vulnerabilities that exposed all Operating Systems (including Widnows and Linux), for more [info](https://www.pcworld.com/article/3245606/security/intel-x86-cpu-kernel-bug-faq-how-it-affects-pc-mac.html).

```terminal
$ sudo apt-get update
$ sudo apt-get upgrade
```

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## Installing packages from the apt store

```terminal
$ sudo apt-get install (package name)
```

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## Installing local `.deb` packages

```terminal
$ sudo dpkg -i (package path)
```

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## Interesting Appliactions

| Category      | package name                          |
| ------------- | ------------------------------------- |
| Music & Video | vlc, rhythm box (shipped with Ubuntu) |
| PDFs          | Okular, Foxit, PdfShuffler            |
| Screenshots   | Shutter                               |
| C++ IDEs      | Qt Creator, Jet-brains CLion, VSCode  |
| Python IDEs   | Pycharm, Anaconda (Spyder)            |
| Web IDEs      | VSCode, Jet-brains WebStorm           |

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## C++ Struct

### Types in C++

--
* Premitive Data Types (PDT), or first-class citizens, such as: `int`, `double`, `char`, etc.
--
* Custom, user-defined types, for example using: `struct` or `enum class`.

---
### `struct` example

Consider the following application:

```c++
double area( double w , double h )
{
    return w * h;
}

int main()
{
    double w = 0, h = 0;

std::cin >> w >> h;

std::cout << area( w, h ) << std::endl;
    return 0;
}
```

---
### `struct` example (cont'd)

Using `struct`:

--
```c++
struct Rectangle
{
    double w;
    double h;
};
```

--
* `Rectangle` is now a custom type, 
--
* consists of two `double`s. 
--
* Think of it as a package.

---
### `struct` example (cont'd)

--
```c++
struct Rectangle
{
    double w; // First member
    double h; // Second member
}; // Don't forget a semicolon here!
```

--
```c++
double area( Rectangle rectangle )
{
    return rectangle.w * rectangle.h;
}
```

--
```c++
int main()
{
    Rectangle rect;
    rect.w = 3;
    rect.h = 5;
    std::cout << area( rect ) << std::endl;
    return 0;
}
```

---
### `struct` example (cont'd)

```c++
struct Rectangle
{
    double w; // First member
    double h; // Second member
}; // Don't forget a semicolon here!
```

```c++
double area( Rectangle rectangle )
{
    return rectangle.w * rectangle.h;
}
```

```c++
int main()
{
    Rectangle rect;
    std::cin >> rect.w >> rect.h;
    std::cout << area( rect ) << std::endl;
    return 0;
}
```