What is the difference between php5.4 and 5.6

The difference between PHP5.4 and 5.6 is: 1. Version 5.6 allows the use of previously defined constants for calculation when defining variables, and allows constants to be used as default values ​​of function parameters, while version 5.4 does not allow this; 2. The 5.6 version namespace supports constants and functions, but the 5.4 version does not.

The operating environment of this article: Windows 10 system, PHP5.6&&PHP5.4 version, Dell G3 computer

What is the difference between php5.4 and 5.6

PHP5.4: Short Open Tag, array abbreviation, Traits, built-in Web server, detailed modifications

PHP5.6: Constant enhancement, variable function parameters, namespace enhancement

Introduction to the differences between PHP5.6 version:

Better constants

When defining constants, previously defined constants are allowed to be used for calculations:

const A = 2;
const B = A + 1;
class C
{
    const STR = "hello";
    const STR2 = self::STR + ", world";
}

Allow constants as function parameter default values:

function func($arg = C::STR2)

Better variable function parameters

Used instead of func_get_args()

function add(...$args)
{
    $result = 0;
    foreach($args as $arg)
        $result += $arg;
    return $result;
}

At the same time, when calling a function, the array can be expanded into function parameters:

$arr = [2, 3];
add(1, ...$arr);
// 结果为 6

Namespace

Namespace supports constants and functions:

namespace Name\Space {
    const FOO = 42;
    function f() { echo __FUNCTION__."\n"; }
}
namespace {
    use const Name\Space\FOO;
    use function Name\Space\f;
    echo FOO."\n";
    f();
}

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