Intro to PHP and MySQL

Class 1

Welcome!

Girl Develop It is here to provide affordable and accessible programs to learn software through mentorship and hands-on instruction.

Some "rules"

  • We are here for you!
  • Every question is important
  • Help each other
  • Have fun

Welcome!

Tell us about yourself.

  • Who are you?
  • What programming experience do you have?
  • What do you hope to get out of the class?
  • If you were a super hero, what would your super power be?

Principles of Development


DRY - Don't Repeat Yourself

Be Lazy

Trust no user (everyone is trying to exploit you)



Downloads

Why not use M(W)AMP?


Everyone on the same setup
Mirror the dev/production environment
Multiple environments on the same machine


Resources

Setup


cd ~
git clone git@github.com:nickdenardis/gdi-core-php.git
cd gdi-core-php/lessons
vagrant up
Visit http://10.10.10.10/

PHP


PHP is a popular general-purpose scripting language that is especially suited to web development.

“PHP: Hypertext Preprocessor”

Server-side language

What can it do?

  • Dynamic generation of web-page content
  • Database interaction
  • Processing of user supplied data
  • Email
  • File handling
  • Text/Image processing
  • Network interaction
  • And more…

Use case


Let's begin


  1. ~/gdi-core-php/lessons/class1/
  2. Rename index.html -> index.php
  3. Add a PHP Block to the top
  4. <?php

?>
<!DOCTYPE html>
...

http://10.10.10.10/class1/practice/index.php

Manual: http://www.php.net/manual/en/language.basic-syntax.phptags.php

Note about PHP short tags


Preferred
<?php 
...
?>

Not Preferred
<?
...
?>

Displaying text



 <?php
    echo 'Text to display';
    print 'More text';
 ?>
 <!DOCTYPE html>
...

We will use 'echo' for simplicity

Single/double quotes


<?php

$great = 'fantastic';

echo 'This is {$great}'; // Single quotes are literal// This is {$great}

echo "This is {$great}"; // Double quotes allow you to evaluate variables
// This is fantastic
?>

Comments



 <?php
    // This is a single line comment
    echo 'Text to display';

    /* This is a comment
     that is spread over
     multiple lines. */
    print 'More text';
 ?>
 <!DOCTYPE html>
 ...

Escaping Characters



<?php
/*  Use the backslash (\) to tell PHP
    to 'ignore' (not interpret) the next character */

echo 'It's time to party!'; // Error

echo 'It\'s time to party!'; // Correct

?>
<!DOCTYPE html>
...

PHP + HTML


<?php

<address class="copyright">
  <span class="adr">
			<span class="street-address"><?php echo $address; ?></span><br />
					<span class="locality"><?php echo $locality; ?></span>,
					<span class="region"><?php echo $region; ?></span>
					<span class="postal-code"><?php echo $post_code; ?></span>
  </span>
  <span class="tel"><?php echo $phone; ?></span>
</address>

Variables


<?php

$a_bool = true;   // a boolean
$a_bool = false;  // a boolean


$an_int = 12;     // an integer

$a_float = 12.345 // a float


$a_str  = "foo";  // a string
$a_str2 = 'foo';  // a string


$an_array = array(1, 2, 3, 4, 5); // an array


$an_object = new Person; // an object


$a_null = NULL   // a null value
Manual: http://www.php.net/manual/en/language.types.php

Dynamically typed

<?php

$a_string = 'Girl Develop It';

echo $a_string;
// Girl Develop It

$a_string = 15;

echo $a_string;
// 15

Type casting
<?php

echo (string)$a_string;
Resource: http://php.net/manual/en/language.types.type-juggling.php

Using variables


Define and change at will

<?php

$var = 'Bob';
$Var = 'Joe';

echo "$var, $Var";      // outputs "Bob, Joe"
echo "{$var}, {$Var}";      // outputs "Bob, Joe"

$4site = 'not yet';     // invalid; starts with a number
$_4site = 'not yet';    // valid; starts with an underscore
$täyte = 'mansikka';    // valid; 'ä' is (Extended) ASCII 228. ($filling = 'strawberries')

Viewing what variables contain


 <?php

$some_variable = 'Contains some text';
var_dump($some_variable);

// print_r($some_variable);

Results:



Concatenation


 <?php

$class = 'Girl Develop It';
$topic = 'PHP & MySQL';

$attending = $class . ' learning ' . $topic;

echo $attending; // Girl Develop It learning PHP & MySQL


Constants


Define once, never change

 <?php

// Valid constant names
define("FOO",     "something");
define("FOO2",    "something else");
define("FOO_BAR", "something more");

// Error, already defined
define("FOO",     "change something");

// Invalid constant names
define("2FOO",    "something");

// This is valid, but should be avoided:
// PHP may one day provide a magical constant
// that will break your script
define("__FOO__", "something");

Using constants


Use like any other variable

 <?php

define('MY_HOMETOWN', 'Detroit');

echo 'Anyone else from ' . MY_HOMETOWN . '?';

Results:



Cannot redefine


 <?php

define('MY_HOMETOWN', 'Detroit');
define('MY_HOMETOWN', 'Chicago');

echo 'Anyone else from ' . MY_HOMETOWN . '?';

Results:


Is defined?


<?php

defined('MY_HOMETOWN'); // returns boolean

// Safe way to define
if ( ! defined('MY_HOMETOWN') )
{
  define('MY_HOMETOWN', 'Detroit');
}

Arithmetic


Example Name Result
-$a Negation Opposite of $a .
$a + $b Addition Sum of $a and $b .
$a - $b Subtraction Difference of $a and $b .
$a * $b Multiplication Product of $a and $b .
$a / $b Division Quotient of $a and $b .
$a % $b Modulus Remainder of $a divided by $b .
$a ** $b Exponentiation Result of raising $a to the $b 'th power. Introduced in PHP 5.6.

Examples


 <?php

echo (5 + 3) . '<br />';         // prints 8
echo (5 - 3) . '<br />';         // prints 2
echo (5 * 3) . '<br />';         // prints 15
echo (5 / 3) . '<br />';         // prints 1.6666...
echo (5 % 3) . '<br />';         // prints 2

Result:


Conditionals


<?php

$color = 'red';

if ($color == 'red') 
{
  echo 'Red is my favorite color too!';
}

if ($color === 'green')
{
  echo 'Such a boring color.';
}
else
{
  echo 'Your color must be sweet!';
}

Conditionals


 <?php

$color = 'red';
$sky_color = 'blue';

if ($color == $sky_color) 
{  echo 'Look up!';}

All the comparison operators


Example Name Result
$a == $b Equal TRUE if $a is equal to $b after type juggling.
$a === $b Identical TRUE if $a is equal to $b, and they are of the same type.
$a != $b Not equal TRUE if $a is not equal to $b after type juggling.
$a <> $b Not equal TRUE if $a is not equal to $b after type juggling.
$a !== $b Not identical TRUE if $a is not equal to $b, or they are not of the same type.
$a < $b Less than TRUE if $a is strictly less than $b.
$a > $b Greater than TRUE if $a is strictly greater than $b.
$a <= $b Less than or equal to TRUE if $a is less than or equal to $b.
$a >= $b Greater than or equal to TRUE if $a is greater than or equal to $b.

"Juggling"


PHP does not require (or support) explicit type definition in variable declaration; a variable's type is determined by the context in which the variable is used.

<?php

$foo = "0";  // $foo is string (ASCII 48)
$foo += 2;   // $foo is now an integer (2)
$foo = $foo + 1.3;  // $foo is now a float (3.3)
$foo = 5 + "10 Little Piggies"; // $foo is integer (15)
$foo = 5 + "10 Small Pigs";     // $foo is integer (15)

Switch

 <?php

$color = 'blue';

switch ($color) {
  case: 'red':
    echo 'Great color!';
    break;

  case: 'blue':
    echo 'That\'s an OK color.';
    break;

  case 'green':
  case 'pink':
  case 'yellow':
    echo 'Really? You like one of those?';
    break;
 
  default:
    echo 'Pick something more unique!';
    break;

}; // notice the ;

Arrays

<?php
$array = array(
    "foo" => "bar",
    "bar" => "foo",
);

// as of PHP 5.4
$array = [
    "foo" => "bar",
    "bar" => "foo",
];

var_dump($array);
?>
Results:


Arrays of Arrays


<?php
$array = array(
    "foo" => "bar",
    "bar" => array(       "baz" => "bat"
    )
);

var_dump($array);
?>


Loops


for
foreach
do-while
do
while
break
continue

For


 <?php

for ($i = 1; $i <= 10; $i++) {
    echo $i;
}

Foreach


 <?php

$arr = array(1, 2, 3, 4);
foreach ($arr as $value) {
    $value = $value * 2;
}

do-while

 <?php

$i = 0;
do {
    echo $i;
} while ($i > 0);

do

 <?php

do {
    if ($i < 5) {
        echo "i is not big enough";
        break;
    }
    $i *= $factor;
    if ($i < $minimum_limit) {
        break;
    }
   echo "i is ok";

    /* process i */

} while (0);

while


 <?php

$i = 1;
while ($i <= 10) {
    echo $i++;  /* the printed value would be
                   $i before the increment
                   (post-increment) */
}

Including other files


 <?php

require '/path/to/file.php'; // Will throw E_COMPILE_ERROR if not found
include '/path/to/file.php'; // Will throw E_WARNING if not found but will continue

require_once 'path/to/file.php';
include_once 'path/to/file.php';

Let's try it!


Break the single page into modules

Problem 1:


You have to add another page to the 'Women in Computing' website.


Task:


Create an easy way to add pages

PHP & MySQL - Class 1 - Girl Develop It

By Nick DeNardis

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PHP & MySQL - Class 1 - Girl Develop It

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