php array negative and positive numbers - php

Question

I have an array of values both positive and negative:
$numbers=['10','-2','-1','8','-7','1','-2','-3'];
I need to echo the results as:
numbers[0]=10;
numbers[1]=8;
numbers[2]=7;
numbers[3]=8;
numbers[4]=1;
numbers[5]=1;
numbers[6]=-1;
numbers[7]=-4;
Basically I take the first value that is always positive, echo that value, subtract the first negative value, echo the results, the second, etc until I found the next positive value, I echo that value, subtract from this value that becomes now reference the second negative value and so on...
I tries this in a loop but I can't manage to "break" the results after finding the second positive number - the numbers keep adding at the result from the first set of positive + negative values - even when using unset....
$i=0;
$sum=0;
while ($i < count($numbers)){
$sum=$sum+$numbers[i];
if($numbers[i]>0)
{
echo $numbers[i];
}
else
{
echo $sum;
}
}

Answer 1

You need to reset $sum to the number whenever you get a positive number.
foreach ($numbers as $i => $num) {
if ($num > 0) {
$sum = $num;
} else {
$sum += $num;
}
echo "numbers[$i] = $sum<br>";
}

Answer 2

$numbers=['10','-2','-1','8','-7','1','-2','-3'];
$i=0;
// there is no need initializing sum here since you it will be the first number
$sum=0;
while ($i < count($numbers)){
// $sum=$sum+$numbers[$i]; This is not needed
if ($numbers[$i] > 0) {
// if the $numbers[$i] is greater than 0 then it is a positive number
// you set $sum to the new positive number
$sum = $numbers[$i];
} else {
//else you perform arithmetic function here
// and since $numbers[$i] is a negetive number adding it will substract from $sum
$sum += $numbers[$i];
}
// You're concern about the sum so you should do your logic before echoing
echo $sum;
// Always remember to increment as while loop wont do that for you
$i++;
}