ceil

(PHP 4, PHP 5)

ceil — 进一法取整

说明

float ceil ( float $value )

返回不小于 value 的下一个整数，value 如果有小数部分则进一位。

参数

value: 要进一法取整的值

返回值

返回不小于 value 的下一个整数。 ceil() 返回的类型仍然是 float ，因为 float 值的范围通常比 integer 要大。

范例

Example #1 ceil() 例子

  <?php
 echo  ceil ( 4.3 );     // 5
 echo  ceil ( 9.999 );   // 10
 echo  ceil (- 3.14 );   // -3
 ?>

参见

floor() - 舍去法取整
round() - 对浮点数进行四舍五入

用户评论:

[#1] Anonymous [2015-11-03 09:22:03]

Just a quick note to be careful of, if you use the "round_up" code suggested by steve, i must warn you it isn't completely fool proof.

I have the following maths which is evaluated incorrectly

37.2000 - 6.2000 = 31.01

echo(round_up(37.2000 - 6.2000,2));

This returns the incorrect result, 31.01 which as any junior in mathematics knows...IS WRONG!

use with caution.

[#2] Bas Vijfwinkel [2015-05-25 03:38:20]

Note that 'ceil' can show unexpected behaviour when using float values due to inaccuracies in the float system and PHP tendency to freely limiting the number of digits it displays to the user.
It might like it is rounding up values that end in 0 (zero) but actually PHP is not showing that the value is not exactly the value it shows.

<?PHP echo('Displaying 13915.0000000000018190 : '. 13915.0000000000018190); echo('<br>'); echo('Result ceil(13915.0000000000018190) :'.ceil(13915.0000000000018190)); echo('<br>'); ?>
For example 13915 cannot be represented as exactly 13915 but becomes
13916.0000000000018190 and 'ceil' will therefore round it up to 13916.

<?PHP $value = 12650 * 1.1; echo('Expected behaviour : ceil(12650 * 1.1) = ceil(13915) = 13915'); echo('<br>'); echo('Using only ceil :'.ceil($value)); echo('<br>'); echo('Showing decimals : '.number_format($value - floor($value), 16)); echo('<br>'); echo('Using ceil + round : '.ceil(round($value,4))); ?>

So if 'ceil' looks like it is not working correctly and rounding up figures that end in 0 (zero) then this might be the cause of this behaviour.
Adding a simple 'round' before the applying the 'ceil' solves this problem.

[#3] cedricaubert at gmail dot com [2015-04-14 15:14:48]

Here is a more accurate way to round on superior decimal.

function round_sup($nb, $precision) {
        $p = pow(10, $precision);
        return ceil(round($nb * $p, 1)) / $p;
}

$k = 10 * 4.98;                   // k = 49.8
echo ceil($k * 10) / 10;    // 49.9   !!
echo round_sup($k, 1);   // 49.8

[#4] Gemini_13 at torba dot su [2014-12-05 12:16:33]

$test = (1 - 0.7) * 10;

$test_1 = ceil($test);
$test_2 = ceil($test * 10);

var_dump($test_1); // float 4
var_dump($test_2); // float 31

[#5] josoort at home dot nl [2014-05-12 07:14:54]

You can simply make a ceil with decimals function by using the round() function and add 0.05 to the value if the value must have 1 decimal accuracy, or 0.005 for 2 decimals accuracy, or 0.0005 for 3 decimals etc.

Example :

function ceilDec($input, $decimals)
{
$subtract = 5 / pow(10, $decimals + 1);
$output = round($input + $subtract, $decimals);
return $output;
}

[#6] eg at pensio dot com [2013-07-29 11:57:38]

Remember that floating point precision means behavior can be "correct" - though not what you expect:

php > echo 100 * 1 * 0.07;
7
php > echo ceil(100 * 1 * 0.07);
8

[#7] alesegdia at gmail dot com [2013-06-16 19:00:37]

Some people asking on rounding -1.5 to -2 and 1.5 to 2, the way is this:

<?php=round($var, 0, PHP_ROUND_HALF_UP)?>

See round() doc for more information on this.

[#8] sebastien dot thevenaz at gmail dot com [2012-07-30 18:20:51]

Here is another way to use ceil for decimal numbers with precision:

<?php function ceil_dec($number, $precision) { $coefficient = pow(10,$precision); return ceil($number*$coefficient)/$coefficient; } ?>

[#9] php is the best [2012-04-20 06:29:54]

Ceil for decimal numbers with precision:

function ceil_dec($number,$precision,$separator)
{
    $numberpart=explode($separator,$number);
$numberpart[1]=substr_replace($numberpart[1],$separator,$precision,0);
    if($numberpart[0]>=0)
    {$numberpart[1]=ceil($numberpart[1]);}
    else
    {$numberpart[1]=floor($numberpart[1]);}

    $ceil_number= array($numberpart[0],$numberpart[1]);
    return implode($separator,$ceil_number);
}

echo ceil_dec(1.125,2,"."); //1.13
echo ceil_dec(-1.3436,3,"."); //-1.343
echo ceil_dec(102938.1,4,"."); //102938.1

[#10] Lexand [2012-03-30 12:15:12]

$k = 0.14 * 100;
echo ceil($k); // results 15

solution is in converting float number to string

Example 1.
echo ceil ("{$k}"); // results 14

Example 2.
$totalSum1 = 102.1568;
$k = $totalSum1 / 100;
echo ceil ("{$k}"); // results 102.16

Example 3.
$totalSum2 = 102.15;
$k = $totalSum1 / 100;
echo ceil ("{$k}"); // results 102.15

useful for 'ceil' with precision capability

[#11] frozenfire at php dot net [2012-02-06 02:38:10]

Please see http://www.php.net/manual/en/language.types.float.php for information regarding floating point precision issues.

[#12] oktam [2011-05-10 03:12:44]

Actual behaviour:
echo ceil(-0.1); //result "-0" but i expect "0"

Workaround:
echo ceil(-0.1)+0; //result "0"

[#13] AndrewS [2011-03-07 04:55:11]

The code below rounds a value up to a nearest multiple, away from zero.  The multiple does not have to be a integer.  So you could round, say, to the nearest 25.4, allowing you to round measurements in mm to the nearest inch longer.

<?php // $x is the variable // $c is the base multiple to round to, away from zero $result =  ( ($y = $x/$c) == ($y = (int)$y) ) ? $x : ( $x>=0 ?++$y:--$y)*$c ; ?>

I originally developed this as an example of write-only code: to make the point that being cleverly terse might save clock ticks but wastes more in programmer time generating un-maintainable code.

The inline code above nests one conditional statement inside another.  The value of y changes twice within the same line (three times, if you count the pre-increment).  The value of each assignment is used to determine branching within the conditional statement.

How it works can more easily be seen from the expansion below:

<?php function myCeilingLong($x,$c) {     // $x is variable     // $c is ceiling multiple     $a = $x/$c ;     $b = (int)$a ;     if ($a == $b)         return $x ;  // x is already a multiple of c;     else     {         if ($x>=0)             return ($b+1)*$c ;  // return ((int)(x/c)+1 ) * c         else             return ($b-1)*$c ;  // return ((int)(x/c)-1 ) * c     } } ?>

<?php function myCeilingShort($x,$c) {     return ( ($y = $x/$c) == ($y = (int)$y) ) ? $x : ( $x>=0 ?++$y:--$y)*$c ; } ?>

Comparing the versions for speed: the in-line version is about three times faster than myCeilingLong() - but this is almost entirely down to function call overhead.

Putting the in-line code inside the function: the difference in execution speed between myCeilingLong() and myCeilingShort() is around 1.5%.

ceil() is still around 25% faster than the in-line statement so if you are a speed hound your efforts might be better devoted to compiling your own library ...

[#14] Scott Weaver / scottmweaver * gmail [2008-08-29 10:46:51]

I needed this and couldn't find it so I thought someone else wouldn't have to look through a bunch of Google results-

<?php // duplicates m$ excel's ceiling function if( !function_exists('ceiling') ) { function ceiling($number, $significance = 1) { return ( is_numeric($number) && is_numeric($significance) ) ? (ceil($number/$significance)*$significance) : false; } } echo ceiling(0, 1000); // 0 echo ceiling(1, 1); // 1000 echo ceiling(1001, 1000); // 2000 echo ceiling(1.27, 0.05); // 1.30 ?>

[#15] themanwe at yahoo dot com [2007-03-20 11:35:13]

float ceil

function fCeil($val,$pressision=2){
     $p = pow(10,$pressision);
    $val = $val*$p;
    $val = ceil($val);
  return $val /$p;
}

[#16] steve_phpnet // nanovox \\ com [2005-02-28 12:40:48]

I couldn't find any functions to do what ceiling does while still leaving I specified number of decimal places, so I wrote a couple functions myself. round_up is like ceil but allows you to specify a number of decimal places. round_out does the same, but rounds away from zero.

<?php // round_up: // rounds up a float to a specified number of decimal places // (basically acts like ceil() but allows for decimal places) function round_up ($value, $places=0) { if ($places < 0) { $places = 0; } $mult = pow(10, $places); return ceil($value * $mult) / $mult; } // round_out: // rounds a float away from zero to a specified number of decimal places function round_out ($value, $places=0) { if ($places < 0) { $places = 0; } $mult = pow(10, $places); return ($value >= 0 ? ceil($value * $mult):floor($value * $mult)) / $mult; } echo round_up (56.77001, 2); // displays 56.78 echo round_up (-0.453001, 4); // displays -0.453 echo round_out (56.77001, 2); // displays 56.78 echo round_out (-0.453001, 4); // displays -0.4531 ?>

[#17] aaron at mind-design dot co dot uk [2004-07-21 13:10:15]

Or for the terniary fans:

<?php function roundaway($num) { return(($num > 0) ? ceil($num) : floor($num)); } ?>

Slightly pointless, but there you have it, in one line only..

[#18] rainfalling at yahoo dot com [2004-04-22 05:51:20]

IceKarma said: "If you want, say, 2.6 to round to 3, and -2.6 to round to -3, you want round(), which rounds away from zero."

That's not always true. round() doesn't work that way, like zomis2k said it just rounds up _or_ down to the nearest non-decimal number. However this should work.

<?php function roundaway($num) { if ($num > 0) return ceil($num); elseif ($num < 0) return floor($num); elseif ($num == 0) return 0; } ?>

[#19] roger_dupere at hotmail dot com [2003-11-10 02:02:55]

Here is a navbar using the ceil function.

<?php function navbar($num_rows,$page,$link) { $nbrlink = 10; $page = (int) $page; $num_rows = (int) $num_rows; if( $num_rows > 0 ) { $total_page = ceil( $num_rows / $nbrlink ); for( $i=1;$i<$total_page+1;$i++ ) { if( $i == $page ) { $ret .= " <b>$i</b> "; } else { if( strstr( $link,"?" ) ) { $ret .= " <a href=\"$link&page=$i\">$i</a> "; } else { $ret .= " <a href=\"$link?page=$i\">$i</a> "; } } } return $ret; } } $navbar = navbar( $num_rows, $page, "listmovie.php?id=$id" ); if( $navbar != null || $navbar != "" ) { print( "<p><div align=\"center\">$navbar</div></p>" ); } ?>