<?php
$arr = array();
for ($i = 0; $i < 1000; $i++) $arr[] = rand(-100, 100);
$start = microtime(true);
for ($i = 0; $i < 1000; $i++){
foreach ($arr as $v) $v = abs($v);
}
echo number_format(microtime(true) - $start, 4).'<br />';
$start = microtime(true);
for ($i = 0; $i < 1000; $i++){
foreach ($arr as $v) if ($v < 0) $v = abs($v);
}
echo number_format(microtime(true) - $start, 4).'<br />';
$start = microtime(true);
for ($i = 0; $i < 1000; $i++){
foreach ($arr as $v) if ($v < 0) $v *= -1;
}
echo number_format(microtime(true) - $start, 4).'<br />';
?>
Result:
1.4061
0.9697
0.2805
Conclusion: better to check before using the feature that the number is less than zero. Even better use multiplication by -1 than this function.
abs
(PHP 4, PHP 5, PHP 7)
abs — Valor absoluto
Parámetros
-
number -
Valor decimal a convertir
Valores devueltos
El valor absoluto de number. Si el
argumento number es
del tipo float, el valor devuelto es también del tipo float,
siendo para los otros casos del tipo integer (debido a que float tiene normalmente
un rango de valores mayor que integer).
Ejemplos
Ejemplo #1 Ejemplo de abs()
<?php
echo abs(-4.2); // 4.2 (double/float)
echo abs(5); // 5 (integer)
echo abs(-5); // 5 (integer)
?>
add a note
User Contributed Notes 2 notes
eep2004 at ukr dot net ¶
2 years ago
Ister ¶
10 years ago
[*EDIT* by danbrown AT php DOT net: Merged user's corrected code with previous post content.]
jeremys indicated one thing - there is no sgn function wich actually seems a bit strange for me. Of course it is as simple as possible, but it is usefull and it is a standard math function needed occasionally.
Well, I have solved this function in a bit different matter:
<?php
function sgn($liczba)
{
if($liczba>0)
$liczba=1;
else if($liczba<0)
$liczba=-1;
else if(!is_numeric($liczba))
$liczba=null;
else
$liczba=0;
return $liczba;
}
?>
The difference is that it returns null when the argument isn't a number at all.
