intdiv

(PHP 7, PHP 8)

intdiv — 整数値の除算

説明

intdiv(int $num1, int $num2): int

num1 を num2 で割った整数商を返します。

パラメータ

num1: 割られる数。
num2: num1 を割る数。

戻り値

num1 を num2 で割った整数商。

エラー / 例外

num2 が 0 の場合、DivisionByZeroError 例外がスローされます。num1 が PHP_INT_MIN で num2 が -1 の場合、 ArithmeticError 例外がスローされます。

例

例1 intdiv() の例

<?php
var_dump(intdiv(3, 2));
var_dump(intdiv(-3, 2));
var_dump(intdiv(3, -2));
var_dump(intdiv(-3, -2));
var_dump(intdiv(PHP_INT_MAX, PHP_INT_MAX));
var_dump(intdiv(PHP_INT_MIN, PHP_INT_MIN));
var_dump(intdiv(PHP_INT_MIN, -1));
var_dump(intdiv(1, 0));
?>

int(1)
int(-1)
int(-1)
int(1)
int(1)
int(1)

Fatal error: Uncaught ArithmeticError: Division of PHP_INT_MIN by -1 is not an integer in %s on line 8
Fatal error: Uncaught DivisionByZeroError: Division by zero in %s on line 9

参考

/ - 浮動小数点数値の除算
% - 整数値の剰余
fmod() - 引数で除算をした際の剰余を返す - 浮動小数点数値の剰余

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User Contributed Notes 3 notes

down

AmeenRoss ¶

9 years ago

This does indeed seem to be equal to intdiv:

<?php
function intdiv_1($a, $b){
    return ($a - $a % $b) / $b;
}
?>

However, this isn't:

<?php
function intdiv_2($a, $b){
    return floor($a / $b);
}
?>

Consider an example where either of the parameters is negative:
<?php
$param1 = -10;
$param2 = 3;
print_r([
    'modulus' => intdiv_1($param1, $param2),
    'floor' => intdiv_2($param1, $param2),
]);

/**
 * Array
 * (
 *     [modulus] => -3
 *     [floor] => -4
 * )
 */
?>

down

oittaa ¶

2 years ago

Python style integer division, where the result is always rounded towards minus infinity.

1 // 2 is 0
(-1) // 2 is -1
1 // (-2) is -1
(-1) // (-2) is 0

<?php
function intdiv_py(int $num1, int $num2): int{
    if ($num1 < 0 xor $num2 < 0){
        $num1 = abs($num1);
        $num2 = abs($num2);
        $remainder = $num1 % $num2;
        return $remainder ? -1 -($num1 - $remainder) / $num2 : -$num1 / $num2;
    }
    return intdiv($num1, $num2);
}

var_dump(intdiv_py(1, 2)); // 0
var_dump(intdiv_py(-1, 2)); // -1
var_dump(intdiv_py(1, -2)); // -1
var_dump(intdiv_py(-1, -2)); // 0
?>

down

-2

sree dot millu at gmail dot com ¶

5 years ago

@AmeenRoss 
This does NOT  seem to be equal to intdiv:

<?php
function intdiv_1($a, $b){
    return ($a - $a % $b) / $b;
}
 ?>

See this example code
<?php 

$x = 5.6;
$y = 1.4 ;

echo intdiv($x,$y);
    
    echo "\n";
    
function intdiv_1($a, $b){
    return ($a - $a % $b) / $b;
}    

echo intdiv_1($x,$y);
?>

//Output
5
4

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