<?php

      // Open our PHP script



      // Here we can write our code. Notice the "//" without the quotation marks We could also use "/* Comment */".

      // We use /* Comment */ when commenting multiple lines instead of manually typing "//" on each individual line.

      // Comment's can only be used inside our PHP script. In HTML5 you would need to use "<!-- These tags to display a comment -->"

      // We can use comment's various of way's. Below is a few ways we can put comments into use.



      // The users name that wins the race.

      $winner = "Derek";



      /**

       * Below we check if the winner of the race is Derek.

       * If the winner of the race is Derek we display Yay!.

       * If it is not Derek we echo Nay!.

      */



      if ($winner === "Derek") {

         echo "Yay!";

      }else {

         echo "Nay!";

      }



      // Closing our PHP script

?>

    

<?php

  // We can use both single and double quotation marks when displaying comments.



  // Example 1

  echo "Some random text.";



  // Example 2

  echo 'More random text.';



  // Both examples above give off the same results, however we can use double quotation marks to work with data.

  // The next example will display our string variable. I show 2 ways of displaying our string.

  // Example 3

  $name = "Derek";

  echo "My name is $name";



  // This way we concatenate our string to our current text being displayed.

  echo 'My name is ' . $name;



?>

    

<?php



  /**

   * Below is the correct way to name your variables although right now my naming convention isn't that great.

   * We are not allowed specify variables with a numerical value after the $ sign. See below.

   * $711 = "value";

   * The above demonstration would give an error. Test this out for yourself and play around with it.

   */



  $value = 711;

  $_value = 117;



?>

    

<?php

  // We can create multiple data types with a variable see below.



  // A String

  $username = "Algebra";



  // An Integer

  $age = 18;



  // A Float / Double Value

  $height = 5.12;



  // A Boolean

  $truth = true;



  // An Array

  $friends = array("Josh", "John", "David");

  // Another way of declaring an array of values: $friends = ["Josh", "John", "David"];

?>

    

<?php



  // Example 1

  echo "Displaying this text to the screen!";



  // Example 2

  echo("Displaying text to the screen");



  // Example 3

  print "This way of outputting is the same as echo except this has a return value (of 1) and echo has not.";



  // Example 4

  print("Echo is slightly faster than me!");



  /**

   * We can also use single quotation marks when displaying text to the screen.

   * I explained the differences between both in the PHP Quotation Marks section.

   */



  echo 'Single Quote output';



  // You can not use single quotes inside single quotes or double quotes inside double quotes.

  // We can use double quotes inside single quotes and single quotes inside double quotes.

  // However you can use them by adding a backslash, see below.



  echo 'on\'t mess with me!';

  echo "\"Don't mess with me\"";



?>

    

<?php

  // Below we set an array of values. Then we access these values inside our array, and then we output them.

  // Arrays start from 0 and iterate each time you add a value. Arrays can hold multiple data types.



  // Remember our "Quotation Marks" section, well the same is expected inside an array when working with strings.

  // I would suggest always using double quotation marks when working with an array of data.

  $team = array("Derek", "Age" => 34, "John");



  // We want to select the first string from our array of data.

  echo "$team[0] scored a goal!";



  // Now we want to select the last string from our array of data.

  echo $team[1] . ' scored an own goal and is now suffering from severe depression, his career is ruined.';



  // We now want to use our Key / Value pair to display Josh's age.

  echo "Josh is $team['Age'] years old!";



  /**

   * You might be confused about the arrays count. Since Age is before John, but since we are specifying a key => value pair

   * We must access that key's value using the name of our key, which is Age. So we would access this by typing $team['Age'].

   * This would then give us that keys value which is 34.

   */

?>

    

<?php

  // In this example we will compare two values a numerous of ways to display different results, using if statements.



  $dereks_age = 21;

  $johns_age = 18;



  // Comparing different types of results that may happen.

  // I use if, elseif, else in the example shown below.

  // If one of our checks is equal to true then it will only execute our code inside that block. The other conditions being checked will be skipped.



  if ($dereks_age > $johns_age) {

     echo "Derek is older than John";

  } elseif ($dereks_age != $johns_age) {

     echo "Derek is not the same age as John.";

  } elseif ($dereks_age == $johns_age) {

     echo "Derek is the same age as John.";

  } elseif ($dereks_age < $johns_age) {

     echo "Derek is younger than John.";

  } elseif ($johns_age <= $dereks_age) {

     echo "John is younger or the same age as Derek.";

  } elseif ($johns_age >= $dereks_age) {

     echo "John is the same age as Derek or older.";

  } else {

     echo "John is older than Derek.";

  }



  /**

   * In the above example we compared multiple results that could happen.

   * Some are the same results but others are not. We are basically asking if it's true or false.

   * The operators we used are listed below. We will go over some more of these in the future sections.

   * [color=blue]==, <=, >=, >, <, !=[/color]

   * Other logical operators we could have used. I would recommend searching up more about these.

   *[color=red] ||, &&, ![/color]

   */

?>

    

<?php

  // Below is an example usage of a switch statement.

  // There is 3 parts of a switch statement. There is the case, break, and default.

  // We discussed what case was in the above synopsis.

  // The break happens when we want to jump to the next case.

  // Finally we have our default. Default is used if we didn't receive the result we were expecting. So we set a default result.



  $age = 18;

  switch ($age) {

      case 15:

          echo "You are 15 years old!";

          break;

      case 16:

          echo "You are 16 years old!";

          break;

      case 17:

          echo "You are 17 years old!";

          break;

      case 18:

          echo "You are 18 years old!";

          break;

      default:

          echo "We could not determine your age!";

  }

?>

    

<?php

  // Below I demonstrate how a for loop operates.

  // I set a variable and iterate through it and increase the value of x on each iteration, see below.



  $x = 0;



  for ($i = 1; $i < 19; $i++) {

      echo ++$x . " of 18" . "<br>";

  }



  // The above for loop will iterate until our variable $i has a value of 19. Which will also echo the line of text 18 times.

  // The above code will echo a line like below 18 times.

  // 1 of 18

  // 2 of 18 etc

?>

    

<?php

  // We will make two foreach constructs. The first example will assign an array to a variable and echo it's value.

  // Example 1:

  $foods = array("Tuna", "Chicken", "Pork", "Beef");



  foreach ($foods as $food) {

      echo "I Love $food";

  }



  // The next example we will use a key => value pair and display our name and age.

  // Example 2:

  $aboutMe = array("Derek" => 18, "Josh" => 21, "John" => 37);



  foreach ($aboutMe as $name => $age) {

      echo "Hey my names $name and my age is $age! <br>";

  }

?>

    

<?php

  // Below I set a numeric value, then use a while loop to iterate until our variable equals our expected value.

  $population = 0;



  while ($population <= 21) {

      echo "Added ". ++$population ." <br>";

  }



  // The above while loop will execute & output our text 21 times.

  // While loops are useful if we want to repeat our condition until our expected result is met.

?>

    

<?php

  // The usage is quite similar to the while loop.

  // However a do while loop always executes our code before our condition is met.

  // Unlike our while loops it first checks our condition then executes our code repeatedly until the condition is met.



  // Example:



  $population = 1;



  do {

      echo "Our population is " . $population++ . "<br>";

  } while ($population <= 21);



?>

    

<?php

  // First we will show the correct way of assigning a constant value.

  // Our constants must be all UPPERCASE and each word divided by an underscore.



  define("AGE", 1;

  define("NAME", "John Doe");

  define("USERS_ADDRESS", "123 Hacker Way");



  // Here we concatenate our constants to our output being displayed.

  echo "My name is " . NAME . " I'm " . AGE . " years old. I live at " . USERS_ADDRESS;



  // The incorrect way of defining constants would be defining them as shown below.



  define("happy", "I'm not happy");

  define("lil_depressed", "Favorite rapper");

  define("50_cent", "2 fiddy");



  // Remember all our constant defined values must all be uppercase and start with a letter followed by an underscore, letters and numbers.

?>

    

<?php

  // Below we create a function that will assign a new value to our $age variable.



  $age = 18;

  $name = "";



  function oneYearLater() {

      $age = 19;

  }



  // We can call this function now since we have created it above.

  oneYearLater();



  // We can not call this function yet as it has not being created yet.

  // name();



  // However now that we have created our function we can call it after it has been parsed.

  function name() {

      $name = "Derek";

  }

  // This will now change our variable $name to the assigned value.

  name();



  // Next we will pass 2 parameters to a function.

  // In our function we will use the parameters in our output.



  function aboutMe($age, $name) {

      echo "My name is " . $name . " I am " . $age . " years old.";

  }



  // Since we assigned a value inside the above functions for each of our variables, we wont get the originally assigned values.

  // This will display My name is Derek I am 19 years old.

  

  aboutMe($age, $name);

?>