PHP Basics
About PHP
Difference between PHP and HTML
HTML isn’t processed until it gets to the browser, but the PHP is executed on the server, and its output(typically HTML or some other text) replaces the PHP code.
PHP is a server-side language. None of your PHP ever hits the browser — it’s processed on the server.
What you can do with PHP
- You’ll be able to change values on your site based on user input or other values (e.g. change the greeting based on the time of day.)
You’ll be able to use the information that a user enters into a form, maybe by giving them appropriate content based on that info (think search results) or by storing that information within a database.
You’ll be able to let your users upload files to your server.
You’ll be able to build pages “on the fly” by combining templates with content from a database, all right as the viewer requests that specific page.
And more and more…
Installing PHP
XAMPP or MAMP
Another tools
How to use php in terminal
php -a //hit enter
The Example Files and codes
PHP files
- Open htdocs folder
- Create a folder called example
Create a file index.php
<?php
echo "The code will go here";
?>
localhost:8888/examples/index.php on your browser.
PHP Syntax
PHP Tags
<?php
//your php code goes here
?>
PHP and HTML
<html>
<title>my php page</title>
<body>
<?php
echo "hello there!";
?>
</body>
</html>
Doing Cool Stuff with PHP and HTML
<h1> Hello PHP! </h1>
<?php
echo "<p>I'm getting good with PHP.</p>";//you need ; for each statement
?>
<?php
echo "<b>hello there!</b>";
?>
<?php
echo "<font color='green'>hello there!</font>";
?>
<?php
echo "today is ".date('Y-m-d');
?>
Variables
$message = "<p>I'm getting good with PHP.</p>";
echo $message;
Basic Values/Datatypes
Strings
Two quotes and sigle quotes
<?php
$str = "It's a nice day today."
echo $str;
?>
<?php
$str = 'This is a PHP string examples in single quotes';
echo $str;
?>
Using a single quote. <?php echo "That's how you do it. 'Gotcha,' you reply."; ?>
Escaping Special Characters
Escaping a quote <?php $str = "\"This is a PHP string examples in double quotes\""; echo $str; ?>
Escaping an apostrophe
<?php
$str = 'It\'s a nice day today.';
echo $str;
?>
you can put variables right inside the string
$name = "Sherlock";
echo "Hello, $name.";
Concatenating Strings in PHP
<?php
$str1 = "I Love PHP.";
$str2 = "PHP is fun to learn.";
echo $str1." ".$str2;
?>
Useful PHP String Functions
Example - strlen() Function
<?php
$str = "Hello!";
echo strlen($str);// 6
?>
Example - str_replace() Function
<?php
$str = "Hello! How are you today?";
echo str_replace("Hello", "Hi", $str);//Hi! How are you today?
?>
Example - strtoupper() Function
<?php
$str = "hello!";
echo strtoupper($str);//HELLO!
?>
Example - ucfirst() Function
<?php
$str = "hello!";
echo ucfirst($str);//Hello!
?>
Example - trim() Function
<?php
$str = " hello! ";
echo trim($str);//"hello!
?>
Numbers
1001.234
-10
1.234e5 //123400
echo 1.23e4 //12300
Booleans
not case-sensitive true/TRUE and false/FALSE.
// return false
"" (empty string)
0
false (of course)
null
array() (an empty array)
Null
caseinsensitive null/NULL
Array
numeric arrays
$an_array = array("HTML", "CSS", "JavaScript", "PHP");
By default, arrays use numeric indices; also by default, the indices start at 0, not 1. So, based on that array up there,
$an_array[0] holds the value HTML
$an_array[2] is JavaScript.
Associative array using key => value
PHP arrays are not confined to one data type per array. $person = array( "name" => "Sherlock Holmes", "birthdate" => "January 6, 1854", "married" => false, "interests" => array("reading", "chemistry", "crime", "violin") ); $person["name"] will be "Sherlock Holmes"
Assigning value to an array
$an_array[4] = "SQL";
$person["best friend"] = "John Watson";
Comments
# this is a comment
// this is also a comment
/* this is
a multiline
comment */
$name = "Sherlock"; # You can add comments here.
$name = "Sherlock"; // You can add comments here as well.
Operators
Arithmetic Operators
$num = 10;
$num = $num + 10; # Addition
$num = $num - 5; # Subtraction
$num = $num / 2; # Division
$num = $num * 0.2; # Multiplication
echo $num; # outputs 1.5
We’re redefining the value of the variable $num every time
Modulus
It returns the remainder. The modulus operator is a great way to find out if a number is odd or even.
//modulus %
5 % 3; # 2
The string operator
"first string " . "second string";// . concatenate strings
Assignment Operators
$num = 10;
$num += 10; # Addition $num = $num + 10
$num -= 5; # Subtraction
$num /= 2; # Division
$num *= 0.2; # Multiplication
echo $num; # outputs 1.5
Incrementing / Decrementing Operators
// all are the same
$num = $num + 1;
$num += 1;
$num++;
$num=5;
echo $num++;//5
num=5;
echo ++$num ;// 6
$num=5;echo $num-- ;//5
$num=5;echo --$num ; //4
Comparison Operators
doubleequals ( == ) and triple-equals ( === )
double-equals (also called the equal operator) tries to convert both values to the same type before comparing.
1 == "1" // true
1 === "1" // false
10 != "10"; # false, because it converts the string to a number
10 !== "10"; # true
5 > 10; # false
5 < 10; # true
5 >= 10; # true
4 <= 4; # true
$name = "Sherlock";
var_dump(!$name)// bool(false)
$married = false;
var_dump(!$married);// trueLogical Operators
//&& AND
var_dump(6 > 5 && 1 < 7); //true
// || OR
var_dump(2 > 5 || 1 < 7);//truePHP If Else Statement
<html>
<body>
<?php
//Give what day of the week it is. Returns Sunday through Saturday.
$day = date("l");
if ($day == "Saturday")
echo "It's party time :)";
else
echo "Ahhh! I hate work days.";
?>
</body>
</html><html>
<body>
<?php
//Give what day of the week it is. Returns Sunday through Saturday.
$day = date("l");
if ($day == "Saturday")
{
echo "It's party time :)";
echo " Where are you going this evening?";
}
else
{
echo "Ahhh! I hate work days.";
echo " I want weekend to come :)";
}
?>
</body>
</html>The Elseif Statement in PHP
<html>
<body>
<?php
//Give what day of the week it is. Returns Sunday through Saturday.
$day = date("l");
if ($day == "Saturday")
{
echo "It's party time :)";
echo " Where are you going this evening?";
}
elseif ($day == "Friday")
{
echo "Have a nice day!";
}
else
{
echo "Ahhh! I hate work days.";
echo " I want weekend to come :)";
}
?>
</body>
</html>