Basic PHP Tutorial (Part 02)

IF ELSE Statements

• Examples of if else syntax

// what will be printed?
$var = true;
if($var){
    echo "var is true!";
}else{
    echo "var is false!";
}

• “” is false
• Empty array is false
• 0 is false

// what will be printed?
$var = "";
if($var){
    echo "var is true!";
}else{
    echo "var is false!";
}

Arrays in PHP

• A simple array

$arr = array("1", "2", "3"); // create an array
echo $arr[1]; // what will be printed?

$arr = ["1", "2", "3"]; // this is the same
echo $arr[1]; // the same!

• In the above we created a simple array.
• Remember: an array starts in index 0.
• Therefore printing the index 1 of the array printed the second element.

$arr = ["1", "2", "3"];
echo $arr[1]; // prints 2

• In PHP we can create arrays with keys. It’s very useful

$arr = ["key1" => "value1", "key2" => "value2"];
echo $arr['key1'];

Loops in PHP

For Loop…..

• Notice the 3 components from left to right: starting the counter, checking some condition, increment the counter.
• Notice the new line character \n

for ($x = 1; $x <= 10; $x++) {
    echo $x . "\n"; // prints 1 2 3 4 … 10 in separate lines 
}

For Each Loop…

• On array by value

// for regular array
$arr = ["1", "2", "3"];
foreach($arr as $element){
    echo $element . "\n"; // prints 1 2 3 in separate lines
}

// for array with keys
$arr = ["key1" => "value1", "key2" => "value2"];
foreach($arr as $element){
    echo $element . "\n"; // prints value1, value2 in separate lines
}

• On array by key and value.

$arr = ["key1" => "value1", "key2" => "value2"];
foreach($arr as $key => $element){
    echo $key . " " . $element . "\n"; // prints key1 value1, key value2 in seperate lines
}

Live Coding

• Iterate over an array of strings and print all strings which are longer then 6 characters in a new line.
• Now print only if they are longer then 6 and shorter then 10.