Rounding Integers

bbisaillon

How can I round an integer upward or downward? For example, roundint($integer, $updown) where $integer is the number you want to round and $updown is the boolean value that tells the function to round the number up (1) or down (0). Does PHP have a function that will at the very least round an integer downwards? I found some functions for floats but not integers.

Purpose: This would be useful for my navigation bar where I want to round down the total number of rows (say it was 54 I want it to round it down to 50) and display the results where Offset = 50 and NumRows = 10. So basically someone can click on "Last Results" to go directly to the last page of results.

LordShryku

Using round() with a negative precision can accomplish this.

bbisaillon

Thanks, I didn't even notice int precision on the manual page.

bbisaillon

I want to round the number down to the nearest zero always. So if it's 54 I want it to round down to 50 and if it's 59 I want it to round down to 50. round() doesn't seem to do this for me.

LordShryku

So why not just find your value by replacing the last number with zero?

$number = 126;
$newNumber = substr($number, -1)."0";
// should be 120

drawmack

Actually Shryku's way doesn't work (at least no on my server) and won't ever work with floating point numbers however you can do this very simply with some modulous arithmetic. Here is the code, just copy and paste to test it out.

<?php
$number = 126; 
$newNumber = substr($number, -1)."0";
$roundToTens = roundToTens($number);
$roundToNumber = roundToNumber($number,25); 

displayOutput($number,$newNumber,$roundToTens,$roundToNumber);

function displayOutput($a,$b,$c,$d) {
    echo "<p>Original Number: " . $a . "<br />\n";
    echo "Shryku's Way: " . $b . "<br />\n";
    echo "Round To Tens: " . $c . "<br />\n";
    echo "Rount To 25: " . $d . "<br />\n";
}

function roundToTens($a) {
  $a = intval($a);
  return ($a - ($a%10));
}  

function roundToNumber($a,$b) {
  $a = intval($a);
  return ($a - ($a%$b));
}
?>

LordShryku

Well if you're going to make me test it :p

I left out the zero.

<?php
$num    = 126;
$newNum = substr($num,0,-1)."0";
echo $newNum;
?>