Detailed explanation of new features of php7

This time I will summarize the new features of php7. The following is a practical case. Let’s follow the editor’s footsteps and take a look.

php7 new features

Scalar type declaration (requires the parameter to be a specific type, if the parameter type does not match, a fatal error will occur in php5 , php7 will throw TypeError exception)

There are two modes: mandatory (default) and strict mode.

Type parameters are:

1. string

2. int

3. Float

4. Bool

They expand other types introduced in PHP5

#         1. Class name

        2. Interface

      3. Array

        4. Callback type

For example:

<span style="font-size:18px;">function sumOfInts(int ...$ints)
{
    return array_sum($ints);
}
var_dump(sumOfInts(2, &#39;3&#39;, 4.1));</span>

Output:
int(9)

Return type declaration

php7 adds support for return type, which is very similar to parameter type declaration Similarly, the return type
declaration specifies the type of the function's return value. The available types are the same as those available in the parameter declaration.

For example:

<span style="font-size:18px;"><?php
function arraysSum(array ...$arrays): array
{
    return array_map(function(array $array): int {
        return array_sum($array);
    }, $arrays);
}
print_r(arraysSum([1,2,3], [4,5,6], [7,8,9]));
以上例程会输出：
Array
(
    [0] => 6
    [1] => 15
    [2] => 24
)</span>

NULL coalescing operator

If If the variable exists and the value is not NULL, it will return its own value, otherwise it will return its second parameter

$username = $_GET['user'] ?? 'nobody';

The results of the upper and lower expressions are the same.

$username = isset($_GET['user']) ? $_GET['user'] : 'nobody';

#Combined comparison operators

is used to compare two expressions. It returns 1, 0 or -1 when $a is greater than, equal to or less than $b respectively.

For example:

<span style="font-size:18px;"><?php
// Integers
echo 1 <=> 1; // 0
echo 1 <=> 2; // -1
echo 2 <=> 1; // 1
// Floats
echo 1.5 <=> 1.5; // 0
echo 1.5 <=> 2.5; // -1
echo 2.5 <=> 1.5; // 1
 
// Strings
echo "a" <=> "a"; // 0
echo "a" <=> "b"; // -1
echo "b" <=> "a"; // 1
?></span>

By define () Define constant array

<?php
define(&#39;ANIMALS&#39;, [
    &#39;dog&#39;,
    &#39;cat&#39;,
    &#39;bird&#39;
]);
echo ANIMALS[1]; // outputs "cat"
?>
php5.6 中 仅能通过const 定义
<?php
const $a = [
     &#39;a&#39;,&#39;b&#39;,&#39;c&#39;,
];
echo $a[1] ; //输出 “b”
?>

Anonymous class ​​​​​​​##​​​​​
Can now support new class To instantiate an anonymous class, this can be used to replace some completion classes that are used only once

Provide filtering for unserialize()

<span style="font-size:18px;"><?php
// 把所有的对象转换为 __PHP_Incomplete_Class object
$data = unserialize($foo, ["allowed_classes" => false]);
// 除了MyClass,MyClass2 都转换为 into __PHP_Incomplete_Class object 
$data = unserialize($foo, ["allowed_classes" => ["MyClass", "MyClass2"]);
// 默认的行为，接受所有的参数
$data = unserialize($foo, ["allowed_classes" => true]);
</span>

IntlChar
The newly added IntlChar class is designed to expose more ICU functions. This class itself defines many static methods for Manipulate unicode characters in multiple character sets

If you want to use this class, you need to install the Intl extension first

ExpectedThe intention is to use backwards and enhance the previous assert() method, which makes enabling assertions in a production environment cost-free and provides the ability to throw characteristic exceptions when assertions fail.

Now assert() is a language construct that allows the first argument to be an expression rather than just a string to be evaluated or a boolean to be tested

Use use to declare a set of classes ## as follows:

<span style="font-size:18px;"><?php
// Pre PHP 7 code
use some\namespace\ClassA;
use some\namespace\ClassB;
use some\namespace\ClassC as C;
use function some\namespace\fn_a;
use function some\namespace\fn_b;
use function some\namespace\fn_c;
use const some\namespace\ConstA;
use const some\namespace\ConstB;
use const some\namespace\ConstC;
// PHP 7+ code
use some\namespace\{ClassA, ClassB, ClassC as C};
use function some\namespace\{fn_a, fn_b, fn_c};
use const some\namespace\{ConstA, ConstB, ConstC};
?>
</span>

Generator return expression

is as follows:

<span style="font-size:18px;"><?php
$gen = (function() {
    yield 1;
    yield 2;
    return 3;
})();
foreach ($gen as $val) {
    echo $val, PHP_EOL;
}
echo $gen->getReturn(), PHP_EOL;// 换行，为了提高源码可读性
以上例程会输出：
1
2
3
</span>

A generator can delegate to another generator

is as follows:

<span style="font-size:18px;"><?php
function gen()
{
    yield 1;
    yield 2;
    yield from gen2();
}
function gen2()
{
    yield 3;
    yield 4;
}
foreach (gen() as $val)
{
    echo $val, PHP_EOL;
}
?>
以上例程会输出：
1
2
3
4
</span>

The integer division function intp()
is added as follows ：

<span style="font-size:18px;"><?php
var_dump(intp(10, 3));
?>
以上例程会输出：
int(3)
</span>

Session options

You can now accept an array parameter through session_start(), which can be written from session in php.ini The configuration instructions parameters support session.lazy_write, read_and_close, cache_limiter, etc.
are as follows:

<span style="font-size:18px;"><?php
session_start([
    &#39;cache_limiter&#39; => &#39;private&#39;,
    &#39;read_and_close&#39; => true,
]);
?>
</span>

New preg_replace_callback_array() function

Can perform better than preg_replace_callback()

##Add two new functions, random_bytes() and random_int()

Please see the following for specific usage methods:

random_bytes()

random_int()
list() no longer supports automatic unpacking

Before, list did not provide guarantees for operating objects that implemented ArrayAccess. Now this problem has been solved

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