system and PHP versions

• system: Centos 64-bit
• PHP 7.2

URL: http://php.net/manual/en/func.

PHP Code:

<?php

    $a = PHP_INT_SIZE;
    $b = PHP_INT_MAX;
    $c = PHP_INT_MIN;

    echo "\$a:", $a . "\n";
    echo "\$b:", $b . "\n";
    echo "\$c:", $c . "\n\n";

    echo "\$b:" . decbin($b) . "\n";
    echo "\$c:" . decbin($c) . "\n";

output result:

$a:8
$b:9223372036854775807
$c:-9223372036854775808

$b:111111111111111111111111111111111111111111111111111111111111111
$c:1000000000000000000000000000000000000000000000000000000000000000

problem description:

• in 64-bit system, the maximum integer value is 9223372036854775807, and the minimum integer value is-9223372036854775808,
The binary of the minimum value of
• is 64 bits, and the 1 of the highest bit is a negative number.
• Why is the maximum binary 63 bits? Did you omit the first 0?

Thank you for the answer