this i my array
$arr = array(1,2,3,4,5);
How to get the result that calculate the value of this expression ((((1-2) -3)-4)-5)?
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You mean like this? : stackoverflow.com/questions/7595255/array-reduce-phphakre– hakre2011-09-29 11:51:15 +00:00Commented Sep 29, 2011 at 11:51
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You mean you want the integer result of that, or that literal string?Jonnix– Jonnix2011-09-29 11:51:17 +00:00Commented Sep 29, 2011 at 11:51
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See the link @hakre posted in that case.Jonnix– Jonnix2011-09-29 11:56:35 +00:00Commented Sep 29, 2011 at 11:56
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6 Answers
2 times the first entry minus the whole sum - looks pretty quick.
echo (2 * reset($arr)) - array_sum($arr);
1 Comment
Paul
Note: The use of reset to get the first element of the array is much better than using $arr[0] because it works with the following: $arr = (-1 => 1, 0 => 2, 1 => 2, 2 => 3, 3 => 4, 4 => 5); $arr = array();
Just substract the sum of all elements but the first from the first element:
echo array_shift($arr) - array_sum($arr); # -13
To preserve the array, change the calculation a little:
echo $arr[0]*2 - array_sum($arr); # -13
And we're glad you didn't ask for eval:
echo eval('return '.implode('-', $arr).';'); # -13
However the best suggestion I can give is that you encapsulate the logic into a class and overload the array with it. So that the object than can provide a method for the calculation (Demo):
class Operands extends ArrayObject
{
public function operate($sign)
{
$sign = max(-1, min(1, $sign.'1'));
$arr = $this->getArrayCopy ();
return $arr[0]*(1-$sign) + $sign*array_sum($arr);
}
public function __invoke($sign) {
return $this->operate($sign);
}
}
$arr = new Operands($arr);
echo $arr('-'), ', ' , $arr('+');
2 Comments
salathe
This changes the array, which may not be desired. Not that that's a good or bad thing, since @newbie never stated the array must remain intact.
hakre
Added some examples that don't do that and - if the calculation is needed multiple times - another example how to "overload" the array. Was not specified in the question either, but might be helpful.
<?php echo eval(implode("-", $arr)); ?>
Comments
Try this:
$arr = array(1,2,3,4,5);
// load the first number to subtract
$result = $arr[0];
$i = 1;
foreach($arr as $item)
{
if ($i !=1) // skip the first one
$result -= $item;
$i++;
}
echo $result;
?>
1 Comment
Mário Rodrigues
Following your example (1-2-3-4-5) should give -13. Is that what you want?
This?
<?php
foreach ($arr as $val)
{
$calc -= $val;
}
echo $calc;
?>
