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https://github.com/sanix-darker/php_learn

php learn
https://github.com/sanix-darker/php_learn

learning php tutorial

Last synced: about 1 year ago
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php learn

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README 

          
## PHP LEARN



Yeah... each statement need to end with a comma ";".... BOOOOO.



## LEARN MAP



![map](./php.svg)



[CHECK THE INTERACTIVE MAP](https://sanix-darker.github.io/php_learn/php.html)



## CONCEPTS



### PRINTERS



```php



echo "ok", 12# can take multiple items, but only print item that can converted to string

print "Hello";# only one item

print("Hello");# only one item



var_export("something");

```



### DATA TYPES



```php



// constants

define("EXAMPLE_CONSTANT", 12);



// Variables and data types :



$str = "Hello";

$bool = true; // or false

$int = 12;

$float = 12.12;



$is_empty = NULL;



$arr = array('Hello', 12, 'there', false);

# to add values to the array (

    - array_push($arr, "item", "item 2"); # to add new items

    - in_array($var, "value"); # to check if a value is in array

    - array_map(function($val) { return "this" }) # apply a method to all items in the arr.

       > $arr_val = ["hello", "this", "and", "that"];

       > $arr_val_Upper = array_map(function($val) {

       >     return strtoupper($val);

       > }, $arr_val);

       > print_r($arr_val_Upper);

    - array_filter($values, fn($nn) => return $condition); # to filter values based on a condition

    - array_reduce()

       > print_r(

       >     array_reduce(["this", "and", "that"], function($a, $b) {

       >         return "{$a} - {$b}";

       >     })

       > );

    - array_pop($arr); # to remove the last added item

    - array_shift($arr); # to remove the first item in the array

    - array_unshift($arr, "prev_value"); # to preppend the array with a new value.

    - unset($arr[3]); # to remove the item [3] from the array.

    - array_chunk($arr, 3); # to split an array into multiple small chunks

    - $arr = array_reverse($arr); # to shift values

    - count($arr); # to count values inside the array

    - # to merge two arrays:

        - array_merge($arr1, $arr2);

        - [...$arr0, ...$arr2];

)

var_dump($arr); //to print the whole content



$hash_map = array(

    'x' => 12, 'y' => 33, 'z' => $arr

);

var_dump($hash_map); // we can also use print_r, it's same but less infos.

// to loop inside an hasmap (assotiative array);

foreach ($hash_map as $key => $value){

    echo $key." ---> ".$value

}

// get keys

array_keys($hash_map);

// get values

array_values($hash_map);

// we can flip keys and values too:

$new_flipped_hashmap_arr = array_flip($hash_map);



// To combine two arrays in a way we have keys -> values

// we could use array_combine();

$final_hash_map = array_combine($arr_keys, $arr_values);

// we can define ranges like in python

$range_10 = range(10);



// Resources Data type (holds a resources).

?>

```



### CONDITIONS



- if / else:



```php



// Note:

// == Equal to

// === Identical to



// != Not Equal to

// !== Not Identical to

if ($user == "this" AND $pass == "xxx") { // AND (&&) | OR (||)

    echo "this";

 }else{

    echo "that";

}

```



- switch /case:



```php



const name_r = "Hlllo";

switch (strlen(name_r)) {

    case 5:

        echo "IT's 5";

        break;

    default:

        echo "OUPS !!!";

        break;

}

```



- ternary:



```php



echo ($content_radian > 10) ? "is upper than 10" : "is lower than 10";



// Usefull to check the variable and the ternary evaluation directly.

echo $post[0] ?? "NULL";

```



### SESSION VARIABLES



Global Session variables :



- `$_GET`: all query params.

- `$_ENV`: for env vars.

- `$_FILES`: contains infos about files uploaded.

- `$_POST`: all POST form params.

- `$_REQUEST`: both.

- `$_SESSION`: session params but needed a `session_start` to be initiated.

    NOTE: to kill a session, it's `session_destroy();`

- `$_COOKIES`: cookies values.

- `$_SERVER`: entries created by the webserver.



### LOOP



- foreach

```php



$items = ['this', 10, 'that']; // array('', ...) works too



foreach ($items as $item){

    echo $item;

}

```

- while



```php



$i = 0;

while($i < 10){

    // do something

    echo "count - ".$i;

    $i += 1;

}

```



- do/while (execute first before checking the condition).

```php



$i = 0;

do {

    echo "--{$i}";

    $i -= 1;

}while($i > 3);

```



- for

```php



for ($i = 0; $i < 10 &i ++;){

    echo $i;

}

```

## BUILTIN FN



```php



rand(1, 100); # for random value in that range

# The list below is pretty obvious i guess...



abs(12.3);

floor(12.3);

ceil(12.3);

round(12.3);

sqrt(9);

pow(3, 4);



max(23, 4, 1, 55);

min(23, 4, 1, 55);



pi(23, 4, 1, 55);



# more practical

isset(); // true if var declared and not null

empty(); // true if not declared or false or null or ""



# date

echo date("H");



// We can filter input _POST to prevent XSS injections

// the big advantages for this is to not have to use isset()

//  each times

$name = filter_input(

    INPUT_POST, # this is know by php itself

    "name",

    FILTER_SANITIZE_SPECIAL_CHARS # this too...(there is multiple tyhpe of FILTER_... mode)

);

echo $name;



// manipulating data

echo var_dump(json_encode($val));



// htmlspecialchars

// to prevent also xss injections

echo htmlspecialchars($tring);

```



### FORMATING



```php



user="dk";

echo "{$user} is connected !";



$amount = 20.23;

// we can also escape characters.

echo "{$user} owned me \${$amount}";



// formating in a C way

printf("%s is %d years old and has $%f", "sanix", 20, 12);

```



### FILE HANDLING



```php



$file = "path.txt"



if (file_exists($file)){

    $handle = fopen($file, 'r');

    $contents = fread($handle, filesize($file));

    fclose($handle);



    echo $contents;

}else{

    $handle = fopen($file, 'w');

    fwrite($handle, $contents);

    fclose($handle);

}

```



### EXCEPTION



```php



function inverse(int $val): float{

    if (!$val){

        throw new Exception('val need to be set');

    }

    return 1/$val;

}



try{

    echo inverse(3);

    echo "
";

    echo inverse(0);

}catch(Exception $e){

    echo "Caught... this and that. {$e}";

}finally{

    echo "always executed.";

}

```



### OOP

```php



class User{

    public string $name;

    public int $age;

    public bool $gender; //true M, false F



    public string $email; // Can not be access from outside



    private $account;

    protected $bank_amount;



    public function __construct(string $name, int $age, bool $gender, string $email){

        $this->name = $name;

        $this->age = $age;

        $this->gender = $gender;

        $this->email = $email;

    }



    public function get_email(): string {

        return $this->email;

    }



    public function set_email(string $given_email): void{

        $this->email = $given_email;

    }

}



$usr = new User("dk", 20, true, "a@b.c");

echo $usr->get_email();

// inheritence

//

class Employee extends User {

    public mixed $custom;



    public function __construct(string $name, int $age, bool $gender, string $email, mixed $custom){

        parent::__construct($name, $age, $gender, $email);

        // new props

        $this->custom = $custom;

    }



    public function get_custom(): mixed{

        return $this->custom;

    }

}

$eee = new Employee("sk", 34, false, "t@b.c", ["a", "b"]);

echo "
";

print_r($eee->get_custom());

```



### EXTRAS



```php



// to include a page to another one

include("this.php");



# or // can be used to define comments



# size of a string var

strlen($var); // to get size of a string

strtolower($var); // to lower string

strtoupper($var); // to upper string

trim($var); // to remove spaces surounding string

// to add a padding of characters after the string

str_pad($var, 10, "-"); // to lower string

str_replace("o", "a", "Hello Warld!");

strrev($var); // to reverse the string

str_shuffle($var); // to shuffle characters in strings

strcmp($var1, $var2); // to compare two strings



strpos($var, "a"); // to the theindex of the first occurence of "a" in $var.

substr($var, 10); // string substract

substr($var, 2, 10); // string substract with a start/end indexes



ucwords($string); // upper each first character for each words.



str_start_with("value", "v"); // check if a string start with something specific.

str_end_with(); // same loggic but with end.



explode(" ", "a b c"); // like a split and return an array.

implode("-", array("a", "b")); // like a join



# hashs method

$hh = password_hash("value", PASSWORD_DEFAULT);

# and to check/verify

password_verify("value", $the_hash_version);



# pass a callback to a method (with default params)

function print_it($callback, $args=array()){

    $callback($args);

}

print_it(

    'print_r', # to pass a callback, it should be defined in params as string.

    array("_GET: " => $_GET),

);



# to deal with checkboxes in php, we need to set the same var that will

# be identify as an array in the backend side.

?>



    

    

    

    



$foods = $_POST["foods"];

# then loop on it

foreach ($foods as $food){

    echo ">>".$food;

}



// cookies

setcookie("key", "value", time() + (100), "/path");

setcookie("this", "that", time() + 100, "/path/to");

// those are stored in $_COOKIES;

// as assotciative array.



// session

// same principle for $_SESSION["values"]



# to get the curret php file

echo $_SERVER["PHP_SELF"];

// the request method made

echo $_SERVER["REQUEST_METHOD"]; # "POST", "GET"



// globals var used in method context.

$this_is_global = 1;

function custom_fn(){

    global $this_is_global;

    echo $this_is_global;

}

custom_fn();



// arrow function

// anonymous function assign to variable

$arrow_fn = fn (int $a, string $b) : int => {

    return strlen($b) + $a;

};

echo $arrow_fn(12, "this is a test");

```