khemputhea

## Week I

* Introduction to Ubuntu 18.04 
* Ubuntu Basic Command & Basic `GIT` usage
* Install PHP, Web Server, Database MySQL
* Introduction to PHP and Syntax Overview
* PHP Variable Types, Constants
* PHP String
* PHP Array
* PHP If...else...elseif
* PHP Switch
* PHP For Loops
* While Loops
* PHP Function
* Lab 1. Form


> Let's get details : 

###  Introducton to Ubuntu 18.04 LTS

Introducton to Ubuntu 18.04 LTS  [here](https://wiki.ubuntu.com/BionicBeaver/ReleaseNotes)

###  Ubuntu Basic Command

> You can try 10 command line on Ubuntu 18.04 LTS  
1. sudo
This SuperUserDo is the most important command Linux newbies will use. Every single command that needs root’s permission, need this sudo command. You can use `sudo` before each command that requires root permissions –
```bash
    sudo su
```

2. ls (list)
Just like the other, you often want to see anything in your directory. With list command, the terminal will show you all the files and folders of the directory that you’re working in. Let’s say I’m in the `/home` folder and I want to see the directories & files in /home. 
```bash
    /home ls
```

3. cd
​Changing directory (cd) is the main command that always is in use in the terminal. It’s one of the most Linux basic commands. Using this is easy. Just type the name of the folder you want to go in from your current directory. If you want to go up just do it by giving double dots (..) as the parameter.
​
Let’s say I’m in /home directory and I want to move in usr directory which is always in the /home. Here is how I can use `cd` commands –

```bash 
    cd /home/username/Desktop
```

4. mkdir
Just changing directory is still incomplete. Sometimes you want to create a new folder or subfolder. You can use mkdir command to do that. Just give your folder name after mkdir command in your terminal.
```bash
    mkdir folderName
```

5. cp
copy-and-paste is the important task we need to do to organize our files. Using `cp` will help you to copy-and-paste the file from the terminal. First, you determine the file you want to copy and type the destination location to paste the file.
```bash
    cp src des
```

> Note: If you’re copying files into the directory that requires root permission for any new file, then you’ll need to use `sudo` command.  

6. rm
`rm` is a command to remove your file or even your directory. You can use `-f` if the file need root permission to be removed. And also you can use `-r` to do recursive removal to remove your folder.
```bash
    rm myfile.txt
```

7. apt-get
This command differs distro-by-distro. In Debian based Linux distributions, to install, remove and upgrade any package we’ve Advanced Packaging Tool (APT) package manager. The apt-get command will help you install the software you need to run in your Linux. It is a powerful command-line tool which can perform installation, upgrade, and even removing your software.​

```bash
sudo apt-get update
```

8. grep
You need to find a file but you don’t remember its exact location or the path. grep will help you to solve this problem. You can use the grep command to help to find the file based on given keywords.
```bash
    grep user /etc/passwd
```

9. cat
As a user, you often need to view some of text or code from your script. Again, one of the Linux basic commands is cat command. It will show you the text inside your file.
```bash
    cat CMakeLists.txt
```
10. poweroff
And the last one is `poweroff`. Sometimes you need to poweroff directly from your terminal. This command will do the task. Don’t forget to add sudo at the beginning of the command since it needs root permission to execute poweroff.

```bash
    sudo poweroff
```


### Install PHP, Web Server, Database MySQL

1. if you are on Ubuntu. Please follow [here](https://www.rosehosting.com/blog/how-to-install-php-7-3-on-ubuntu-16-04/) 
2. If you are window. Please install [Warm Server](http://www.wampserver.com/en/), [Xampp Server](https://www.apachefriends.org/index.html)

### Introduction to PHP and Syntax Overview

1. Introduction to PHP

`PHP` started out as a small open source project that evolved as more and more people found out how useful it was. Rasmus Lerdorf unleashed the `first version of PHP` way back in `1994`.
* `PHP` stand for `Hypertext Preprocessor`
* `PHP` is a server side scripting language that is embedded in HTML. It is used to manage dynamic content, databases, session, tracking, even build entire e-commerce sites. 
* It is intergrated with a number of popular databases, including MySQL, PostgreSQL, Oracle, Sybase, Informix, and Microsoft SQL Server.
* PHP suport a large number of majors protocol such as POP3, IMAP, and LDAP, from `PHP4` added support for Java and distributed ojbect architectures. 

2. Syntax Overview

The PHP parsing engine needs a way to differentiate PHP code from other elements in the page. There are four ways to do this

* Canonical PHP tags
    The most universally effective PHP tag style is: 

    ```bash
        
    ```
* Short-open tags
    Short or short-open tags look like this 
    ```bash
        
    ```
* ASP-Style 
    ASP-style tags mimic the tag used by Active Server Pages to delineate code blocks.

    ```bash
        <% 

        %>
    ```
* HTML script tags
    HTML script tags look like this 
    ```bash
        
    ```

###  PHP Variable Types, Constants

> Here are the most important things to know about variables in PHP.
* All variables in PHP are denoted with a leading dollar sign `$`.
* The value of a variable is the value of its most recent assignment.
* Variables are assigned with the `=` operator, with the variable on the left-hand side and the expression to be evaluated on the right.
* Variables can, but do not need, to be declared before assignment.
* Variables in PHP do not have intrinsic types - a variable does not know in advance whether it will be used to store a number or a string of characters.

* Variables used before they are assigned have default values.

* PHP does a good job of automatically converting types from one to another when necessary.


1. PHP Variable Types

    * Integers: are whole numbers, without a decimal point like 2019.
    * Doubles:  are flaoting-point numbers, like 3.14159, or 201.9.
    * Booleans: have only two possible values either `true` or `false`.
    * NULL: is a special type that only has one value NULL.
    * Strings: are sequences of characters 
    * Array: are nmae and indexed collections of other values.
    * Ojbects: are instances of programmer-defined classes.
    * Resources: are special vairables that hold references to resources external to PHP(such as database connections)

2. PHP Constant 

What is PHP Constant ? 

* A constant is a name or an identifier for a simple value
* A constant value cannot change during the execution of the script
* By default, a constant is case-sensitive
* By convention, constant identifiers are always uppercase. A constant name starts with a letter or underscore, followed by any number of letters, numbers, or underscores

```bash

```
* We define constant `MINSIZE` with value 50.
* We print out `MINSIZE` value.
* We use `constant()` function to get value of `MINSIZE`

> Note: Only scalar data (boolean, integer, float and string) can be contained in constants.

### PHP String

> They are sequences of characters, PHP supports string operations.

1. String Concatenation Operator

    To concatenate two string variables together, we us dot(`.`) operators.

    ```bash
        
    ```


2. Get The Length of a String

    The `strlen()` function is used to find the lenght of a string. 
    ```bash
        echo strlen("web development course");
    ```

3. Search For a Specific Text Within a String

    The `strpos()` function is used to search for a string or character with a string.

    ```bash 
    
    ```

4. Count The Number of Words in a String

    PHP `str_word_count()` function is used to count the number of word in a string. 

    ```bash
        
    ```

5. Reverse a String

    The PHP `strrev()` function reverses a string. 
    ```bash 
        
    ```
    please try to reverse: `web development course` to `course development web`. 

6. Replace Text Within a String

    The PHP `str_replace()` function replaces some characters with some other characters in string.

    ```bash
        
    ```

### PHP Array

> An array is a special variable, which can hold more than one value at a time.

```bash 
    $cars1 = "Volvo";
    $cars2 = "BMW";
    $cars3 = "Toyota";
```

1. Create an Array in PHP

    In PHP, there are three types of arrays:
    
    * Indexed arrays - Arrays with a numeric index
        ```bash 
            $cars = array("Volvo", "BMW", "Toyota");
        ```
        The index can be assigned automatically.  the index can be assigned manually:
        ```bash
            $cars[0] = "Volvo";
            $cars[1] = "BMW";
            $cars[2] = "Toyota";
        ```

    * Associative arrays - Arrays with named keys
        ```bash
            $age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
        ```
        or 
        ```bash 
            $age['Peter'] = "35";
            $age['Ben'] = "37";
            $age['Joe'] = "43";
        ```
        Associative arrays are arrays that use named keys that you assign to them.
        


    * Multidimensional arrays - Arrays containing one or more arrays

### PHP IF else elseif 

1. PHP IF Else Statment

    In if  Statements Output will appear when only Condition must be true.
    > If Statement works  much like the English language statement, “if X happens, then do Y.”

```bash
    if (condition)
        code to be executed if condition is true;
    else
        code to be executed if condition is false;
```
> let check example:

```bash
    
    
    
        
    
    
    
```

> Exercise 1. Write a PHP program to check whether the given number is a `negative` or `positive` number.   

> Exercise 2. Write a PHP program to check whether the given number is a `odd` or `even` number. 


2. The ElseIf Statement

If you want to execute one code of the several condtion are true. We use `elseif` statment

> Syntax 

```bash

    if (condition)
         code to be executed if condition is true;
    else if (condition)
         code to be executed if condition is true;
    else
        code to be executed if condition is false;

```


### PHP Switch 

If you want to select one of many blocks of code to be executed

```bash 


```

> We can use default switch case statement. By use keyword : `default`

### PHP For Loop

> In `for loop` specified condition is predifined. 

```bash
    for (initialization; condition; increment){
        code to be executed;
    }
```

Example : 
```bash
    
    
        
        
    
    
    
```

### PHP While Loop

> `while loop` executes the statement while the specific condition is true. 

```bash
    while (condition) {
        code to be executed;
    }
```  

Example: 

```bash
    
    
    
        
        
    
    

```


### do-while 

> `do-while loop` execute the statement then check the condition, it mean if the condition is false in that case `one time` statement execute. 

```bash
    do {
        code to be executed;
    } while (condition);
```

Example: 

```bash
    html>
    
      
    

#include <iostream>
using namespace std;

int main()
{
    int n;

    cout << "Enter an integer: ";
    cin >> n;

    if ( n % 2 == 0)
        cout << n << " is even.";
    else
        cout << n << " is odd.";

    return 0;
}