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: http://serversforhackers.com/editions/2014/02/25/vagrant-apache/

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

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

Manual: http://php.net/echo

http://www.php.net/manual/en/language.basic-syntax.instruction-separation.php

http://php.net/manual/en/language.types.string.php#language.types.string.syntax.heredoc

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>
 ...

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

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>
...

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

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')

Manual: http://www.php.net/manual/en/language.variables.basics.php

Viewing what variables contain

 <?php

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

// print_r($some_variable);

Results:

Manual: http://php.net/var_dump

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:

Manual: http://www.php.net/manual/en/language.constants.php

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');
}

Manual: http://php.net/defined

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.

Manual: http://www.php.net/manual/en/language.operators.arithmetic.php

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!';
}

Manual: http://www.php.net/manual/en/language.operators.comparison.php

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)

Manual: http://www.php.net/manual/en/language.types.type-juggling.php

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 ;

Manual: http://php.net/manual/en/control-structures.switch.php

Arrays

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

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

var_dump($array);
?>

Results:

Manual: http://php.net/manual/en/language.types.array.php

Arrays of Arrays

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

var_dump($array);
?>

Loops

for

foreach

do-while

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';

Manual: http://php.net/manual/en/function.require.php
http://.php.net/manual/en/function.include.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

Intro to PHP and MySQL

Class 1

Welcome!

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

Downloads

Why not use M(W)AMP?

Resources

Setup

PHP

What can it do?

Use case

Let's begin

Note about PHP short tags

Displaying text

Single/double quotes

Comments

Escaping Characters

PHP + HTML

Variables

Dynamically typed

Using variables

Viewing what variables contain

Concatenation

Constants

Using constants

Cannot redefine

Is defined?

Arithmetic

Examples

Conditionals

Conditionals

All the comparison operators

"Juggling"

Switch

Arrays

Arrays of Arrays

Loops

For

Foreach

do-while

do

while

Including other files

Let's try it!

Problem 1:

Task:

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?