I have an :
$arr = array(321,0.4,0.8,1.2);
$result = array_reduce($arr,create_function('$op1,$op2','return $op1-=$op2;'));
echo $result; //the result should be 318.6, but i got -323.4
would you please tell me what's wrong with this?
4 Answers
The array_reduce function has 3 parameters. The 3rd is $initial.
This is by default NULL. You should fill this one too. Look here: http://nl.php.net/array_reduce
If the optional initial is available, it will be used at the beginning of the process, or as a final result in case the array is empty.
1 Comment
Shef
Why a down vote on this? This is the answer. On the first function call it will be
null -= 321 which will result to -321, then on the consequent calls it will be -321 -= 0.4, ...Just substract the sum of all elements but the first from the first element:
echo array_shift($arr) - array_sum($arr); # 318.6
Comments
Try...
array_reduce($arr,
create_function('$op1,$op2','print "$op1, $op2\n";
return $op1-=$op2;'));
and all should become clear.
Comments
You are using the array_reduce in the wrong way. The first item in the array needs to be shifted out of the array and used as the initial value.
$arr = array(321,0.4,0.8,1.2);
$initial = array_shift($arr);
$result = array_reduce($arr, create_function('$op1,$op2','return $op1-=$op2;'), $initial);
echo $result;
2 Comments
Sophy SEM
$arr = array(1,2,3,4,5,6); $initial = array_shift($arr); $result = array_reduce($arr, create_function('$op1,$op2','return $op1=-$op2;'),$initial); echo $result; I need something like ((((1-2)-3)-4)-5)-6 = -19, but result above is not the same like what i need, please kindly help me. Thanks
Xyz
You have an error in your statement. $op1=-$op2 should be $op1-=$op2. The -= means "take left, substract right and save to left" while =- only means "save negative of right to left".
318.6with$arr = array(321,0.4,0.8,1.2); $result = array_reduce($arr,create_function('$op1,$op2','return $op1-=$op2;'), $arr[0]*2); echo $result;