Как найти целые числа php

IP to BIGINT:
<?php
  $ipArr    = explode('.',$_SERVER['REMOTE_ADDR']);
  $ip       = $ipArr[0] * 0x1000000
            + $ipArr[1] * 0x10000
            + $ipArr[2] * 0x100
            + $ipArr[3]
            ;
?>

IP as BIGINT read from db back to dotted form:

Keep in mind, PHP integer operators are INTEGER -- not long. Also, since there is no integer divide in PHP, we save a couple of S-L-O-W floor (<division>)'s by doing bitshifts. We must use floor(/) for $ipArr[0] because though $ipVal is stored as a long value, $ipVal >> 24 will operate on a truncated, integer value of $ipVal! $ipVint is, however, a nice integer, so
we can enjoy the bitshifts.

<?php
        $ipVal = $row['client_IP'];
        $ipArr = array(0 =>
                    floor(  $ipVal               / 0x1000000) );
        $ipVint   = $ipVal-($ipArr[0]*0x1000000); // for clarity
        $ipArr[1] = ($ipVint & 0xFF0000)  >> 16;
        $ipArr[2] = ($ipVint & 0xFF00  )  >> 8;
        $ipArr[3] =  $ipVint & 0xFF;
        $ipDotted = implode('.', $ipArr);
?>

var_dump((int) "010"); //output 10

First one is octal notation so the output is correct. But what about the when converting "010" to integer. it should be also output 8 ?
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Answer :

Casting to an integer using (int) will always cast to the default base, which is 10.

Casting a string to a number this way does not take into account the many ways of formatting an integer value in PHP (leading zero for base 8, leading "0x" for base 16, leading "0b" for base 2). It will simply look at the first characters in a string and convert them to a base 10 integer. Leading zeroes will be stripped off because they have no meaning in numerical values, so you will end up with the decimal value 10 for (int)"010".

Converting an integer value between bases using (int)010 will take into account the various ways of formatting an integer. A leading zero like in 010 means the number is in octal notation, using (int)010 will convert it to the decimal value 8 in base 10.

This is similar to how you use 0x10 to write in hexadecimal (base 16) notation. Using (int)0x10 will convert that to the base 10 decimal value 16, whereas using (int)"0x10" will end up with the decimal value 0: since the "x" is not a numerical value, anything after that will be ignored.

If you want to interpret the string "010" as an octal value, you need to instruct PHP to do so. intval("010", 8) will interpret the number in base 8 instead of the default base 10, and you will end up with the decimal value 8. You could also use octdec("010") to convert the octal string to the decimal value 8. Another option is to use base_convert("010", 8, 10) to explicitly convert the number "010" from base 8 to base 10, however this function will return the string "8" instead of the integer 8.

Casting a string to an integer follows the same the logic used by the intval function:

Returns the integer value of var, using the specified base for the conversion (the default is base 10).
intval allows specifying a different base as the second argument, whereas a straight cast operation does not, so using (int) will always treat a string as being in base 10.

php > var_export((int) "010");
10
php > var_export(intval("010"));
10
php > var_export(intval("010", 8));
8

<?php// You may expected these
var_dump(0x7fffffffffffffff);                // int(9223372036854775807)
var_dump(0x7fffffffffffffff + 1);            // float(9.2233720368548E+18)
var_dump((int)(0x7fffffffffffffff + 1));     // int(9223372036854775807)
var_dump(0x7fffffffffffffff + 1 > 0);        // bool(true)
var_dump((int)(0x7fffffffffffffff + 1) > 0); // bool(true)
var_dump((int)'9223372036854775807');        // int(9223372036854775807)
var_dump(9223372036854775808);               // float(9.2233720368548E+18)
var_dump((int)'9223372036854775808');        // int(9223372036854775807)
var_dump((int)9223372036854775808);          // int(9223372036854775807)

// But actually, it likes these

var_dump(0x7fffffffffffffff);                // int(9223372036854775807)
var_dump(0x7fffffffffffffff + 1);            // float(9.2233720368548E+18)
var_dump((int)(0x7fffffffffffffff + 1));     // int(-9223372036854775808)   <-----
var_dump(0x7fffffffffffffff + 1 > 0);        // bool(true)
var_dump((int)(0x7fffffffffffffff + 1) > 0); // bool(false)                 <-----
var_dump((int)'9223372036854775807');        // int(9223372036854775807)
var_dump(9223372036854775808);               // float(9.2233720368548E+18)
var_dump((int)'9223372036854775808');        // int(9223372036854775807)
var_dump((int)9223372036854775808);          // int(-9223372036854775808)   <-----?>

These overflows are dangerous when you try to compare it with zero, or substract it from another value (e.g. money).

<?php

var_dump

(010); // int(8) NOT int(010)
var_dump(0x10); // int(16) NOT int(0x10)
var_dump(0b10); // int(2) NOT int(0b10) ?>

This is the reason why casting integer to string gives us always a decimal:

<?php

var_dump

((string) 010); // string(8) NOT string(010)
var_dump((string) 0x10); // string(16) NOT string(0x10)
var_dump((string) 0b10); // string(2) NOT string(0b10)?>

for example
echo(dechex("2724838310"));
will print '7FFFFFFF'
but it should print 'A269BBA6'

When adding '+0' php will handle the 32bit unsigned integer
correctly
echo(dechex("2724838310"+0));
will print 'A269BBA6'

                                                                                    function parse_unsigned_int($string) {
        $x = (float)$string;
        if ($x > (float)2147483647)
            $x -= (float)"4294967296";
        return (int)$x;
    }

IP to BIGINT:
<?php
  $ipArr    = explode('.',$_SERVER['REMOTE_ADDR']);
  $ip       = $ipArr[0] * 0x1000000
            + $ipArr[1] * 0x10000
            + $ipArr[2] * 0x100
            + $ipArr[3]
            ;
?>

This can be written in a bit more efficient way:
<?php
  $ipArr    = explode('.',$_SERVER['REMOTE_ADDR']);
  $ip       = $ipArr[0]<<24
            + $ipArr[1]<<16
            + $ipArr[2] <<8
            + $ipArr[3]
            ;
?>

shift is more cheaper.

-2147483648 falls into the range of 32 bit signed integers yet php treats it as a float.  However, -2147483647-1 is treated as an integer.

The following code demonstrates:
<?php
    var_dump(-2147483648); //float(-2147483648)
    var_dump(-2147483647 - 1); //int(-2147483648)
?>

This is probably very similar to the MS C bug which also treats -2147483648 as an UNSIGNED because it thinks it's out of the range of a signed int.

The problem is that the parser does not view "-x" as a single token, but rather as two, "-" and "x".  Since "x" is out of the range of an INT, it is promoted to float, even though in this unique case, "-x" is in the range of an int.

The best cure is probably to replace "-2147483648" with "0x80000000", as that is the hexadecimal equivalent of the same number.

Hope that helps explain what's going on

Peace

- Eric / fez

0x5468792130ABCDEF

echoes to:

6.0822444802213E+18 (cast to float)

On a fully 64 bits system, it echoes to:

6082244480221302255

<?php
/*
* build the program's capability - define variables and functions...
*/
$item_label = '';        // type string
$item_price = 0.0;       // type float
$item_qty = 1;           // type integer
$item_total = 0.0;       // type float - to set use calculate()function calculate(){
  global $item_price, $item_qty, $item_total;
  $item_price = number_format($item_price, 2);
  $item_total = number_format(($item_price * $item_qty), 2);
}

function

itemToString() {
  global $item_label, $item_price, $item_qty, $item_total;
  return "$item_label [price=$$item_price, qty=$item_qty, total=$$item_total]";
}/*
* run the program - set data, call methods...
*/
$item_label = "Coffee";
$item_price = 3.89;
$item_qty = 2;
calculate();           // set $item_total
echo itemToString();   // -> Coffee [price=$3.89, qty=2, total=$7.78]$item_label = "Chicken";
$item_price = .80;     // per lb.
$item_qty = 3.5;       // lbs.
calculate();           // set $item_total
echo itemToString();   // -> Chicken [price=$0.80, qty=3.5, total=$2.80]
?>
Note: All type-casting is done by PHP's built-in number_format() method. This allows our program to enter any number (float or int) on item price or quantity in the runtime part of our script. Also, if we explicitly cast values to integer in the capability part of our script, then we start getting results that may not be desirable for this program. For example, if in the calculate method we cast item_qty to integer, then we can no longer sell chicken by the pound!

$seed = ($seed * $a + $c) % $m;

...where $m, $a, and $c are values and data types carefully chosen such that repeating this operation will eventually generate every value in the range $0 to $m, with no repetition.

I can find no good commonly used LCGs which use PHP-compatible values. The LCG values used in by rand() in systems like Borland Delphi, Virtual Pascal, MS Visual/Quick C/C++, VMS's MTH$RANDOM, old versions of glibc, Numerical Recipes, glibc, GCC, ANSI C, Watcom, Digital Mars, CodeWarrior, IBM VisualAge C/C++, java.util.Random, Newlib, MMX... *all* fail when ported, for one of two reasons, and sometimes both:

- In PHP on 32 bit machines and all Windows machines, $m = 2^32 or larger requires UInt or even UInt64, or the result becomes negative.

- Large $a multiplied by an integer seed gets converted to a float64, but the number can be too long for the 53-bit mantissa, and it drops the least significant digits... but the LCG code above requires that the most significant digits should be lost.

These are two classes of problem to beware of when porting integer math to PHP,  and I see no clean and efficient way to avoid either one.

So if designing a cross-platform system that must work in PHP, you must select LCG values that fit the following criteria:
$m = 2^31 or less (PHP limitation). Recommend: 2^31.
$a = Less than 2^22 (PHP limitation); $a-1 divisible by all prime factors of $m; $a-1 divisible by 4 if $m is. Recommend: 1+(4*(any prime <= 1048573)).
$c = smaller than (2^53-($m*$a)) (PHP limitation); relatively prime with $m. Recommend: any prime <= 23622320123.

function iplongtostring($ip)
{
    $ip=floatval($ip); // otherwise it is capped at 127.255.255.255

    $a=($ip>>24)&255;
    $b=($ip>>16)&255;
    $c=($ip>>8)&255;
    $d=$ip&255;

    return "$a.$b.$c.$d";
}