PHP Reference

Creating & Accessing

//You create an array using the array() function
$animals=array();

//Can also create and fill an array using array() function
$kids = array(“Van”, “Indigo”, “Jack”, “Regine”);

To access the elements in an array – use the index number. Can store the element in a variable:

$kid1 = $kids[0];

Set any item of the array by doing this:

 $kids[0]  = “Tom”;

Print the Contents of an array

These two methods are used for debugging print_r() prints all the values and var_dump() prints values and data types.

 $kids  = array (“Van ”, “Indigo ”, “Jack ”, “Regine ”); 
 sort($kids);
 print_r($kids);

Output
Array ( [0] => Indigo [1] => Jack [2] => Regine [3] => Van ) 

 var_dump($kids);

Output
array(4) { [0]=> string(6) "Indigo" [1]=> string(4) "Jack" [2]=> string(6) "Regine" [3]=> string(3) "Van" }

indexed

Basic one- array has a numeric key so you access an item in the array using that index number.

 $colors= array (“red ”, “blue ”, “green”);
//access the items in the array using the index value - starting at 0
 echo "Item 1 is ".$colors[0];

Associative

This type of array allows you to store information in pairs. Examples include: A list of students with grades or a list of states with capitol cities.
You use the key value to access the desired data value. In the example below, you use the name of the state as the key value to access its capital city.

Example

//create the array using key values and a new character - the => 
 $capitals= array(“Alabama”=>"Montgomery", “Alaska"=>"Juneau”, “Arkansas”=>"Little Rock");

//access the items in the array using the key value 
 echo "The capital of Alaska is ".$capitals["Alaska"];

Multidimensional

Basically arrays can be made of arrays!

 $students= array (
      array(
          "name"=> "Margot", 
          "age"=> 13,
          "animal"=> "monkey",
          "food"=> "pasta"
      ),

     array(
          "name"=> "Hadley", 
          "age"=> 13,
          "animal"=> "penguin",
          "food"=> "broccoli"
      )
);
      
//use the print_r() or the var_dump() statement to see content and structure

Here are a few useful ones - but here is a full list from W3Schools.

count($kids)

sort($kids)

list($kid1, $kid2)=array("Jack","Jane")

array_pop("$kids")

array_[push("$kids,"Jamal"")

strrev("how long?")

for Loops

<?php 
 for ($x = 0; $x < 3; $x++) {
     echo "The number is: $x <br>";
} 
?>

Output:
The number is 0
The number is 1
The number is 2

foreach Loops

<?php 
   $summer = array(“camp”,”beach”,”pool”,”boredom”); 
   foreach ($summer as $activity) {
      echo “$activity<br>";
   } 
 ?>

Output:
camp
beach
pool
boredom

Nested Loops

You can place loops inside of loops - the outer loop only repeats after the inner loop is done.

for ($i=0; $i < 3; $i++){
   for ($j=1; $j < 3; $j++){
    echo "$i is ".$i." and $j is ".$j);
   }
}

The output will be:
   i is 0 and j is 1
   i is 0 and j is 2
   i is 1 and j is 1
   i is 1 and j is 2
   i is 2 and j is 1
   i is 2 and j is 2

   x  =  1
   while x <= 3:
       print (“The number is”, x)
       x +=1

  Output:
The number is 0
The number is 1
The number is 2
The number is 3

Remember - you can use break to exit a loop - but sparingly.

 <?php
   $x  =  1;
   while ($x <= 300) {
       echo “The number is: $x <br>”;
       $x++;
      if($x == 3){
         break;
      }
   } 
?>
Output:
The number is 0
The number is 1
The number is 2

function myFunction($a, $b) {
  return $a * $b;
}

var $x = myFunction(4,3);
echo("the sum is " + $x);

<form action="script.php" method="post"> </form>

• action – where the form contents will be sent to - usually a PHP script written that processes the data and does something with it.
• method – specifies the way the information will be sent - get or post.

The get Method

This is the default method that is used. It attaches the forms information onto a web address so that it is visible in the URL. For example if a form asks for a first and last name like this:

  <form name="form1" action="myscript.php" method="get">
     <p>First Name:<input type="text" name="firstName"></input></p>
     <p>Last Name:<input type="text" name="lastName"></input></p>
     <input type="submit" name="submit" value="submit">
   </form>

This URL is sent to the web browser:

https://labcatscode.com/myscript.php?firstName=Jack&lastName=Bartlett

Anyone can see the information - used with short forms and forms that do not contain sensitive or private information.  Often used with search queries.

Getting Values using the GET Method

To retrieve and store the form values in a variable name, your PHP would look like this:

<?php 
    $firstName = $_GET[‘firstName’];
    $lastName = $_GET[‘lastName’];
?> 

The Post Method

This method essentially sends the information invisibly to the script which processes it. Used when you are sending lots of information or sensitive information - especially passwords.

Every input element must have a name attribute to be sent correctly with this method. That is so the script that receives it can figure out which field the data belongs to.

Getting Values Using the POST Method

• If we have a form input called first_name that was sent via POST, would be stored as $_POST['first_name'].

In this example, your input field would look like this:

First Name:<input type=“text” name=“firstName”>

In your PHP script, you would retrieve and store the form value in a variable like this:

$firstName = $_POST[‘firstName’];

Redirecting a form to itself - SAFELY

Use this in your action value to redirect the form back to the same PHP page.

User Name:<input type="text" name="username" value="<?php echo $usrname;?>">

User Name:<input type="text" name="username" value="<?php echo htmlspecialchars($usrname);?>">

Storing your Password

Use the bit of code below to turn the password into as hashed version - then store the hashed version in the database.

$hashed_pwd = password_hash('mypassword', PASSWORD_DEFAULT);

Verifying The Password

When you need to verify it you can pull it out using the password_verify() function which has this basic syntax:

password_verify(string $password, string$hashed_password):bool

This will return false if the passwords did not match and true if they did.

if (password_verify('mypassword', $hashed_pwd)) {
   echo 'Password is valid!';
} else {
   echo 'Invalid password.';
}

Function names should:

• start with a verb
• describe what the function does
• use the CamelCase naming convention
• Examples:

function GetRecords()
function CreateUser()
function ViewTable()

Variable names should:

• describe what type of information or data the variable holds
• be written using lowercase with underscores - no spaces!
• avoid using ambiguous variables like $i or $x unless you are doing a simple index or counter in a loop!