ceil

(PHP 4, PHP 5, PHP 7, PHP 8)

ceil — 进一法取整

说明

ceil(int|float $num): float

如果有必要，通过对 num 向上取整返回下一个最高的整数。

参数

num: 要进一法取整的值

返回值

返回不小于 num 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 int 要大。

更新日志

版本	说明
8.0.0	`num` 不再接受支持数字转换的内部对象。

示例

示例 #1 ceil() 示例

<?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

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用户贡献的备注 21 notes

down

Scott Weaver / scottmweaver * gmail ¶

16 years ago

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

?>

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eep2004 at ukr dot net ¶

6 years ago

Caution!
<?php
$value = 77.4;
echo ceil($value * 100) / 100;         // 77.41 - WRONG!
echo ceil(round($value * 100)) / 100;  // 77.4 - OK!

down

emoore at thunkit dot biz ¶

1 year ago

Casting to an int can fix the floating point issue when doing math and then calling ciel(...)

echo PHP_EOL;
$value = 77.4;
$value1 = (int) ($value * 100);
echo $value1;   // 7740
echo PHP_EOL;
$value2 = ((int) ($value * 100))/100;
echo $value2; // 77.4
echo PHP_EOL;
echo ceil($value1) . " ceil step"; // 7740
echo PHP_EOL;
echo ceil(7740.00000) . " ciel a float"; // 7740
echo PHP_EOL;
echo ceil($value * 100); // 7741
echo PHP_EOL;
echo ceil($value * 100) / 100;         // 77.41 - WRONG!
echo PHP_EOL;
echo ceil(round($value * 100)) / 100;  // 77.4 - OK!

down

aaron at mind-design dot co dot uk ¶

20 years ago

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..

down

oktam ¶

13 years ago

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

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

down

steve_phpnet // nanovox \\ com ¶

19 years ago

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
?>

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frozenfire at php dot net ¶

12 years ago

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

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Gemini_13 at torba dot su ¶

9 years ago

$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

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roger_dupere at hotmail dot com ¶

21 years ago

Here is a navbar using the ceil function.



<?php

 function navbar($num_rows,$page,$link) {

   $nbrlink = 10; /* Number of link to display per page */

   $page = (int) $page; /* Page now displayed */

   $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;

   }

 }

  /* Let say that $num_rows content the numbre of rows of your sql query */

  $navbar = navbar( $num_rows, $page, "listmovie.php?id=$id" );



  if( $navbar != null || $navbar != "" ) {

    print( "<p><div align=\"center\">$navbar</div></p>" );

  }

?>

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AndrewS ¶

13 years ago

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 ...

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Bas Vijfwinkel ¶

9 years ago

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.

down

Lexand ¶

12 years ago

$k = 0.14 * 100;
echo ceil($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

down

rainfalling at yahoo dot com ¶

20 years ago

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;
}

?>

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themanwe at yahoo dot com ¶

17 years ago

float ceil

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

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eep2004 at ukr dot net ¶

6 years ago

Caution!
<?php
$value = 77.4;
echo ceil($value * 100) / 100;            // 77.41 - WRONG!
echo ceil((string)($value * 100)) / 100;  // 77.4 - OK!

down

alesegdia at gmail dot com ¶

11 years ago

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

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

See round() doc for more information on this.

down

eg at pensio dot com ¶

11 years ago

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

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sebastien dot thevenaz at gmail dot com ¶

12 years ago

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;
    }
?>

down

php is the best ¶

12 years ago

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

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cedricaubert at gmail dot com ¶

9 years ago

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

down

-5

Anonymous ¶

9 years ago

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.