Features New to PHP7

Posted: Updated: By Blake Cerecero

These notes are from a LinkedIn Learning Course that can be found here: https://www.linkedin.com/learning/php-7-new-features

Scalar Type Declarations

Three Techniques:

  • None: returns as-is
  • Coercive: coerces value before returning it
  • Strict: raises error if type does not match

None

function sum($a, $b) {
    echo $a . " " . gettype($a) . " + ";
    echo $b . " " . gettype($b) . " = ";
    $result = $a + $b;
    echo $result . "" . gettype($result);
}

sum(2, 3);
// 2 integer + 3 integer = 5 integer
sum("2", "3");
// 2 string + 3 string = 5 integer
sum(2.0, 3.0);
// 2 double + 3 double = 5 double

Coercive

function sum(int $a,int $b) {
    echo $a . " " . gettype($a) . " + ";
    echo $b . " " . gettype($b) . " = ";
    $result = $a + $b;
    echo $result . "" . gettype($result);
}

sum(2, 3);
// 2 integer + 3 integer = 5 integer
sum("2", "3");
// 2 integer + 3 integer = 5 integer
sum(2.0, 3.0);
// 2 integer + 3 integer = 5 integer

Strict

declare(strict_types=1);

function sum(int $a,int $b) {
    echo $a . " " . gettype($a) . " + ";
    echo $b . " " . gettype($b) . " = ";
    $result = $a + $b;
    echo $result . "" . gettype($result);
}

sum(2, 3);
// 2 integer + 3 integer = 5 integer
sum("2", "3");
// TypeError: Argument must be of the type integer, string given
sum(2.0, 3.0);
// TypeError: Argument must be of the type integer, float given

Types

  • array
  • bool
  • float
  • int
  • string

Return Type Declarations

Three Techniques:

  • None: returns as-is
  • Coercive: coerces value before returning it
  • Strict: raises error if type does not match

None

function sum($a, $b) {
    return $a + $b;
}

echo gettype(sum(2, 3));
// integer
echo gettype(sum("2", "3"));
// integer
echo gettype(sum(2.0, 3.0));
// double

Coercive

function sum($a, $b): int {
    return $a + $b;
}

echo gettype(sum(2, 3));
// integer
echo gettype(sum("2", "3"));
// integer
echo gettype(sum(2.0, 3.0));
// integer

Strict

declare(strict_types=1);

function sum($a, $b): int {
    return $a + $b;
}

echo gettype(sum(2, 3));
// integer
echo gettype(sum("2", "3"));
// integer
echo gettype(sum(2.0, 3.0));
// TypeError: Return value must be of the type integer, float returned

Combined Comparison Operator

Also known as:

spaceship operator

Comparison Operators

  • ==, ===
  • !=, !==
  • <, <=
  • > , >=

Combined Comparison Operator

  • <=>
$swatch_price <=> $rolex_price
  • Returns -1 when left side is less than right side.
  • Returns 0 when both sides are equal.
  • Returns 1 when left side is greater then right side.

Example 1:

Switch case.

$a = 100;
$b = 200;

switch($a <=> $b) {
    case -1:
        echo '$a is less than $b'; break;
    case 0:
        echo '$a is equal to $b'; break;
    case 1:
        echo '$a is greater than $b'; break;
}

Example 2:

Sort array by price.

$watches = array(
    array('brand': 'Swatch', 'price': 50.0),
    array('brand': 'Timex', 'price': 5.0),
    array('brand': 'Rolex', 'price': 500.0)
);

// Sort by price, in ascending order
function sort_by_price($watch1, $watch2) {
    return $watch1['price'] <=> $watch2['price'];
}

usort($watch, 'sort_by_price');

When watch1 before watch2 ascending order.
When watch1 after watch2 descending order.

Null Coalescing Operator

What it looks like: ??

Returns first value that exists and is not NULL

Example 1:

$value = $user_value ?? $default_value;

Same as:

if (isset($user_value)) {
    $value = $user_value;
} else {
    $value = $default_value;
}

Examples:

echo $page_title ?? 'My Cool PHP App';

$username = $_POST['username'] ?? 'guest';

$value = $a ?? $b ?? $c ?? $d ?? $default;