Round DOWN to nearest half integer in PHP

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I need a PHP function that will take a float and round it down to the nearest half (x.0 or x.5). I found other functions that will round to the nearest fraction, but they round both ways.

The function I need can only round down.

Examples

7.778 -> 7.5

7.501 -> 7.5

7.49 -> 7.0

7.1 -> 7.0

$x = floor($x * 2) / 2;

round - Manual, PHP: Round to the Nearest 0.5 (1.0, 1.5, 2.0, 2.5, etc.) I came up with a slightly more sophisticated solution than but the round() function: Use one of the following constants to specify the mode in which rounding occurs. Round val up to precision decimal places away from zero, when it is half way there. Making 1.5 into 2 and -1.5 into -2. Round val down to precision decimal places towards zero, when it is half way there.

I'm assuming PHP has a floor function: floor($num * 2) / 2 ought to do it.

PHP: Round to the Nearest 0.5 (1.0, 1.5, 2.0, 2.5, etc.), I need a PHP function that will take a float and round it down to the nearest half (x​.0 or x.5). I found other functions that will round to the nearest fraction, but they  Rounds number up to precision decimal, when it is half way there. Rounds 1.5 to 2 and -1.5 to -2. PHP_ROUND_HALF_DOWN - Round number down to precision decimal places, when it is half way there. Rounds 1.5 to 1 and -1.5 to -1. PHP_ROUND_HALF_EVEN - Round number to precision decimal places towards the next even value.

A easy solution is to use modulo operator (fmod() function), like this :

function roundDown($number, $nearest){
    return $number - fmod($number, $nearest);
}

var_dump(roundDown(7.778, 0.5));
var_dump(roundDown(7.501, 0.5));
var_dump(roundDown(7.49, 0.5));
var_dump(roundDown(7.1, 0.5));

And the result :

The advantage it's that work with any nearest number (0.75, 22.5, 3.14 ...)

You can use the same operator to roundUp :

function roundUp($number, $nearest){
    return $number + ($nearest - fmod($number, $nearest));
}

var_dump(roundUp(7.778, 0.5));
var_dump(roundUp(7.501, 0.5));
var_dump(roundUp(7.49, 0.5));
var_dump(roundUp(7.1, 0.5));

Round DOWN to nearest half integer in PHP, PHP: Round to the Nearest 0.5 (1.0, 1.5, 2.0, 2.5, etc.) thinking and testing, I came up with a slightly more sophisticated solution than but the round() function:. Rounding numbers with PHP. round() The round() function rounds the number passed in to the specified number of decimal places. If the decimal places is a negative number ceil() The ceil() function rounds up to the nearest integer (ceil = ceiling). There is no argument for precision so it will

You can do it on that way round($number / 5, 1) * 5 the second parameter in the round() is the precision.

Example with $number equal to 4.6, 4.8 and 4.75

>>> round(4.6 / 5, 1) * 5;
=> 4.5
>>> round(4.8 / 5, 1) * 5;
=> 5.0
>>> round(4.75 / 5, 1) * 5;
=> 5.0

If you want you can round() down too like round($number, 1, PHP_ROUND_HALF_DOWN) check the documentation for more information https://www.php.net/manual/en/function.round.php

PHP: Round to the Nearest · GitHub, The round() function rounds a floating-point number. Tip: To round a number UP to the nearest integer, look at the ceil() function. Tip: To round a number DOWN to the nearest integer, look at the floor() function. PHP’s round() function takes a decimal number (a.k.a. floating point number) and rounds up or down. In its most simple and default form, it will round the decimal to the nearest whole number. For example, round(3.457) will give you the result 3. If you want to keep some of those decimal points, you can add in a precision argument. The default

echo round($val*2) / 2;    // Done

PHP round() Function, Ceil() takes the number and rounds it to the nearest integer above its current value, is exactly half way between two integers, round() will always round up. The floor() function rounds a number DOWN to the nearest integer, if necessary. Tip: To round a number UP to the nearest integer, look at the ceil() function. Tip: To round a floating-point number, look at the round() function.

Rounding: ceil(), floor(), and round() – Hacking with PHP, accepts a single parameter value which reperesents the number which you want to round up to the nearest greater integer. echo round(299792, -3); // 300000. When I’m trying to aggregate all the customer ratings for a specific provider in one of my web hosting reviews community, I want to round the average rating to the nearest 0.5 (half the decimal) so that a half star would be correctly displayed. This is more of a mathematical problem than a PHP one.

PHP floor() Function, I need a PHP function that will take a float and round it down to the nearest half (x​.0 or x.5). I found other functions that will round to the nearest  Hi all Could you please guide me to how to round a decimal number to nearest half using php. eg. 2.213 => 2.5 2.76 => 3.0 3.03 => 3.5 With thanks.

Different ways to round number to 2 decimal places in PHP, It will be rounded to the nearest whole number which is 5. For an integer, 12, it rounds off to 12; For a decimal number, if the last digit after the  For example, if rounding the number 2.7 to the nearest integer, 2.7 would be rounded to 3. Rounding Methods. There are various rounding definitions that can be used to round a number. The calculator defaults to rounding to the nearest integer, but settings can be changed to use other rounding modes and levels of precision.

Comments
  • possible duplicate of PHP round decimals
  • @Artefacto - not a duplicate, that question says nearest (which may be higher), this question says nearest lower or equal (i.e. only ever go down).
  • I can add that you also can use ceil and round depending on how the integer should be rounded.
  • does this work? won't ieee754 problems break this? for example, what happens if you pass the expression 25/4 to a function that does this? Mathematically, you should get 6.5. By IEEE754 will give you 6 instead.
  • @JoelCoehoorn this answer will give you 6 and not 6.5. I swapped floor out for round and seemed to get satisfactory results.
  • Wrong, because the OP only wants to round down.
  • Converting a number to a string to calculate is really awkward