1. Working with Variables
<?php
namespace Codecademy;

$first = "Welcome to the magical world of built-in functions.";

$second = 82137012983;

//Write your code below:

echo gettype( $first ), "\n";
echo gettype( $second ), "\n";

echo var_dump( $first ), "\n";
echo var_dump( $second ), "\n";

/*********************************/
2. String Functions
<?php
namespace Codecademy;

// Write your code below:

echo strrev(".pu ti peeK .taerg gniod er'uoY"), "\n";
echo strtolower("SOON, tHiS WILL Look NoRmAL."), "\n";

echo str_repeat("\nThere's no place like home.\n", 3);

/*********************************/
3. Working with Substrings

<?php
namespace Codecademy;

$essay_one = "I really enjoyed the book. I thought the characters were really interesting. The plot of the novel was really engaging. I really felt the characters' emotions. They were really well-written. I really wish the ending had been different though.";

$essay_two = "Obviously this is a really good book. You obviously would not have made us read it if it wasn't. I felt like the ending was too obvious though. It was so obvious who did it right away. I think the thing with the light was obviously a metaphor for life. It would have been better if the characters were less obvious about their secrets.";

// Write your code below:

echo substr_count( $essay_one, "really" );
echo substr_count( $essay_two, "obvious" );

/*********************************/
4. Number Functions

<?php
namespace Codecademy;

// Write your code below:

function calculateDistance( $num1, $num2 ) {
  $distance = abs($num1 - $num2);
  return $distance;
}
echo calculateDistance(-1, 4), "\n";

function calculateTip( $meal_cost ) {
  $tip = ($meal_cost * 18) / 100;
  $total = $meal_cost + $tip;
  return round( $total );
}
echo calculateTip(100), "\n";
echo calculateTip(88.77);

/*********************************/
5. Generating Random Numbers

<?php
namespace Codecademy;

// Write your code below:
echo getrandmax();
echo "\n";
echo rand();
echo "\n";
echo rand(1,52);

/*********************************/
6. Documentation
<?php
namespace Codecademy;

$a = 29;
$b = "You did it!";
$c = STR_PAD_BOTH;
$d = "*~*";

// Write your code below:
echo str_pad($b, $a, $d, $c);

/*********************************/
7.Finding Functions
<?php
namespace Codecademy;

// Write your code below:

function convertToShout( $shout ) {
  return strtoupper($shout) . "!\n";
}

echo convertToShout("woah there, buddy");
echo convertToShout("i just don't know");

function tipGenerously( $meal ) {
  $tip = ( $meal * 20 ) / 100;
  $total = ceil( $meal + $tip );
  return $total;
}

echo tipGenerously(982.27);

function calculateCircleArea( $diameter ) {
  return pi() * ( $diameter/2 )**2;
}
echo calculateCircleArea(29);