Question

I have wrote this code:

$final = array(
    ($data[0] - $data[1]),
    ($data[1] - $data[2]), 
    ($data[2] - $data[3]),
    ($data[3] - $data[4]),
    ($data[4] - $data[5]), 
    ($data[5] - $data[6]) 
);

Some of them will return negative numbers (-13,-42 etc…), how to change the negative ones to 0?

By the way the think i do after is:

$data_string = join(",", $final);

Example: I need to convert it like in the following:

1,3,-14,53,23,-15 => 1,3,0,53,23,0

Answer 1

I like Hakre’s compact answer. However, if you have a more complex requirement, you can use a function:

<?php

$data = array(11,54,25,6,234,9,1);

function getZeroResult($one, $two) {
    $result = $one - $two;
    $result = $result < 0 ? 0 : $result;

    return $result;
}

$final = array(
    getZeroResult($data[0], $data[1]),
    getZeroResult($data[1], $data[2]), 
    getZeroResult($data[2], $data[3]),
    getZeroResult($data[3], $data[4]),
    getZeroResult($data[4], $data[5]), 
    getZeroResult($data[5], $data[6]) 
);

print_r($final);

?>

http://codepad.org/viGBYj4f (With an echo to show the $result before test.)

Which gives you:

Array
(
    [0] => 0
    [1] => 29
    [2] => 19
    [3] => 0
    [4] => 225
    [5] => 8
)

Note, you could also just return the ternary:

function getZeroResult($one, $two) {
    $result = $one - $two;
    return $result < 0 ? 0 : $result;
}

As well as using it in a loop:

<?php

$data = array(11,54,25,6,234,9,1);

function getZeroResult($one, $two) {
    $result = $one - $two;
    echo "$one - $two = $result\n";
    return $result < 0 ? 0 : $result;
}

$c_data = count($data)-1;
$final = array();

for ($i = 0; $i < $c_data; $i++) {
    $final[] = getZeroResult($data[$i], $data[$i+1]);
}

print_r($final);

?>

http://codepad.org/31WCbpNr