Variable handling 函数
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is_numeric

(PHP 4, PHP 5)

is_numeric — 检测变量是否为数字或数字字符串

描述

bool is_numeric ( mixed $var )

如果 var 是数字和数字字符串则返回 TRUE，否则返回 FALSE。

参见 is_bool()、is_float()、is_int()、is_string()、is_object()、is_array() 和 is_integer()。

Variable handling 函数
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PHP手册 - N: 检测变量是否为数字或数字字符串

用户评论:

dave dot marr at gmail dot com (31-Jan-2012 12:30)

If you want the numerical value of a string, this will return a float or int value:

function get_numeric($val) {
  if (is_numeric($val)) {
    return $val + 0;
  }
  return 0;
}

Example:
get_numeric('3'); // int(3)
get_numeric('1.2'); // float(1.2)
get_numeric('3.0'); // float(3)

akam at akameng dor com (23-Jan-2012 05:22)

<?php
$d = @$_GET['d'];

/*
assuming that passing value of d in the mysql
$sql = "select * from books where bookid = '$d' "
*/

/*
now check if $d is numeric?
*/

if(!is_numeric($d)){
 $d = preg_replace("/[^0-9]+/", "", $d);
}
echo "Cleared value: $d \n<br />Original Vlaue:".@$_GET['d'];
//then using clear value of $d in the mysql query
$sql = "select * from books where bookid = '$d' ";
?>
Example:
?d=52;d;s;s'2233l'[[22

Outpt:

Cleared value: 52223322
Original Vlaue:52;d;s;s'2233l'[[22

holdoffhunger at gmail dot com (30-Dec-2011 05:20)

I wanted an Is_hex function that does the same as is_numeric, except for hex.  Here's one with decent efficiency that uses direct iteration.  $result stores the result as a TRUE/FALSE string (which can be changed to bool, depending on how you want to implement it), and $string_to_test is the string of possible-hex values you want to test.

<?php

    // Released Under Affero General Public License, Version 3 (AGPL3)
    // Author: holdoffhunger@gmail.com

$result = "TRUE";

$testable_string = strtolower($string_to_test);
$testable_string_length = strlen($string_to_test);

for($i_string = 0; $i_string < $testable_string_length; $i_string++)
{
    $current_value_to_test = $testable_string[$i_string];
   
    if(    ($current_value_to_test != "0")        &&
        ($current_value_to_test != "1")        &&
        ($current_value_to_test != "2")        &&
        ($current_value_to_test != "3")        &&
        ($current_value_to_test != "4")        &&
        ($current_value_to_test != "5")        &&
        ($current_value_to_test != "6")        &&
        ($current_value_to_test != "7")        &&
        ($current_value_to_test != "8")        &&
        ($current_value_to_test != "9")        &&
        ($current_value_to_test != "a")        &&
        ($current_value_to_test != "b")        &&
        ($current_value_to_test != "c")        &&
        ($current_value_to_test != "d")        &&
        ($current_value_to_test != "e")        &&
        ($current_value_to_test != "f")        )
    {
        $result = "FALSE";
        $i_string = $testable_string_length;
    }
}

?>

sobolanx at gmail dot com (22-Jan-2011 11:55)

Note that the function accepts extremely big numbers and correctly evaluates them.

For example:

<?php
    $v = is_numeric ('58635272821786587286382824657568871098287278276543219876543') ? true : false;
   
    var_dump ($v);
?>

The above script will output:

bool(true)

So this function is not intimidated by super-big numbers. I hope this helps someone.

PS: Also note that if you write is_numeric (45thg), this will generate a parse error (since the parameter is not enclosed between apostrophes or double quotes). Keep this in mind when you use this function.

Martyn Ranyard (10-Jan-2011 12:14)

The documentation does not clarify what happens if you the input is an empty string - it correctly returns false in my experience.  Useful to state these odd cases, for when you see code that checks for an empty string and is_numeric, you can tell it's a waste of a comparison.

Nitrogen (12-Sep-2010 06:40)

I find it a little weird that people are having issues with ordinal numbers, it's pretty easy..
Notes are in the commenting, check out the example outputs.

<?php

function ordinal($i='') {
  // a temporary value we can change, and keep the original value.
  $o=$i;

  // suffixes = 0th, 1st, 2nd, third == zeroth, first, second, third
  $s=array('th','st','nd','rd');

  // if input just so happens to be a string, we check to make sure it
  // still holds a numeric value and only acquire the last 2 numbers.
  // if it's not a string, nor an integer, we freak out and say no.
  if(!is_int($o))
    if(ctype_digit($o))
      $o=(int)substr($o,-2,2);
    else
      return(false);

  // basically, if $o is between 11 and 19, we use 'th'
  // otherwise we use the last digit and if it's over
  // 4 then we use 0 (for the $s array index).
  return($i.$s[($o%100>10&&$o%100<20)?0:($o%10<4?$o%10:0)]);
}

var_dump(ordinal(5));

/* Example Outputs of ordinal():
  0th, 1st, 2nd, 3rd, 4th, ..., 9th,
  10th, 11th, 12th, 13th, 14th, ..., 19th,
  110th, 111th, ..., 199th, 200th, 201st.

  ordinal('-1'); returns false because ctype_digit hates anything that
  isn't strictly 0 through 9 and '-' trips it to false.

  ordinal('asdf'); returns false for the exact same reason.

  ordinal(); returns false because it's blank.

  signed integers on a 32-bit system (and the same issue on a 64-bit
  system using 0x7FFFFFFFFFFFFFFF because of two's compliment,
  anything higher will become a negative number):
  ordinal(0x7FFFFFFF  ); returns 2147483647th (which is correct)
  ordinal(0x7FFFFFFF+1); returns false.
*/

?>

derek dot p dot moore at gmail dot com (22-Jul-2010 05:39)

To verify large hex numbers or hexadecimal strings use:
http://php.net/ctype_xdigit

purdue at nc dot rr dot com (19-May-2010 12:57)

I see a lot of examples below to get the ordinal string for a given number ("1st", "2nd", "3rd", "4th", etc).  If you only need small ordinals (up to "31st" at most), this one-line trick works:

<?php

function ordinal ($i) {
   return date("jS", strtotime("Jan $i"));
}

?>

dustout at gmail dot com (03-Mar-2010 02:38)

I had troubles when using this as an is_hex function, if anyone else runs into troubles here is an alternative approach. Not a very efficient one, but it worked quite well for what i needed it for.

<?php
function is_hex($hexValue){
if($hexValue == dechex(hexdec($hexValue)))
        return true;
    return false;
}
?>

Kiam (23-Jul-2009 07:02)

empty(trim($test, '+-.,0123456789')) doesn't assure you $test contains a number. It returns TRUE also for a string containing ".+1234.56", which is not a valid number.

codeslinger at compsalot dot com (15-Jul-2009 09:34)

if speed is important, the liberal use of regex should be avoided, especially complex ones like those here.

For most purposes, this will be sufficient and has the advantages of both speed and clarity.

$BoolResult = empty(trim($Test, '+-.,0123456789'));

If the $Test contains any character that is not a valid part of a number the remaining string will not be empty.

if you want to be more restrictive of the '+-'  then you can use a separate trim for that and nest it.  Keep in mind that some notations pt the sign to the right of the number instead of to the left.  Depending upon your specific application you can also choose to ignore spaces and allow for 'e' notation.

I also use this approach when testing for other character sets such as Hex.

info at DriaConsulting dot Com (05-Jul-2009 07:34)

is_numeric() does not escape the string. It validates it's numeric nature with true/false.

However, (int) before the string, converts the string to numeric.

Magnus Deininger, dma05 at web dot de (07-Jan-2009 02:01)

regarding the global vs. american numeral notations, it should be noted that at least in japanese, numbers aren't grouped with an extra symbol every three digits, but rather every four digits (for example 1,0000 instead of 10.000). also nadim's regexen are slightly suboptimal at one point having an unescaped '.' operator, and the whole thing could easily be combined into a single regex (speed and all).

adjustments:

<?php
$eng_or_world = preg_match
  ('/^[+-]?'. // start marker and sign prefix
  '(((([0-9]+)|([0-9]{1,4}(,[0-9]{3,4})+)))?(\\.[0-9])?([0-9]*)|'. // american
  '((([0-9]+)|([0-9]{1,4}(\\.[0-9]{3,4})+)))?(,[0-9])?([0-9]*))'. // world
  '(e[0-9]+)?'. // exponent
  '$/', // end marker
  $str) == 1;
?>

i'm sure this still isn't optimal, but it should also cover japanese-style numerals and it fixed a couple of other issues with the other regexen. it also allows for an exponent suffix, the pre-decimal digits are optional and it enforces using either grouped or ungrouped integer parts. should be easier to trim to your liking too.

nadim (nadim at alienworkers dot com) (04-Nov-2008 09:53)

Using SpT_King James example, i've re-wrote to cater for digits starting with '+', commas ',' or period '.'

<?php
function is_numeric_regex($str)
{
    $str    = "{$str}";

    if (in_array($str[0], array('-', '+')))    $str = "{$str[0]}0" . substr($str, 1);
    else $str = "0{$str}";

    $eng    = preg_match ("/^[+,-]{0,1}([0-9]+)(,[0-9][0-9][0-9])*([.][0-9]){0,1}([0-9]*)$/" , $str) == 1;
    $world    = preg_match ("/^[+,-]{0,1}([0-9]+)(.[0-9][0-9][0-9])*([,][0-9]){0,1}([0-9]*)$/" , $str) == 1;

    return ($eng or $world);
}
?>

jbezorg at gmail dot com (08-Oct-2008 12:50)

"$e = (int) substr( $n , -2 );"

What the heck am I thinking.

<?php
function number_suffix2($n)
{
    $s = array( 1->'st' , 2=>'nd' , 3=>'rd' );
    $e = $n % 100;
    $x = $n % 10;
  
    return $n.( ( $x > 0 && $x < 4 && ( $e < 11 || $e > 13 ) ) ? $s[$x] : 'th' );
}
?>

vezquex at gmail dot com (28-Jul-2008 02:13)

I needed a number_suffix function that was really sweet.
<?php
function number_suffix($n){
{
    $suffix = 'th';
    if(!($n >= 10 && $n < 20));
    {
        $s = ['st','nd','rd'];
        $s = $s[$n % 10 - 1];
        $suffix = $s ? $s : 'th';
    }
    return $n . $suffix;
}
?>

SpT_King James (tiagovix2000 (at) gmail) (11-Jan-2008 06:31)

To Elwin van Huissteden, by his answer at 27-Mar-2007 05:05.

Your code didnt work (you said not tested it). So i fixed it:

<?
function my_is_numeric($value)  {
    $american = preg_match ("/^(-){0,1}([0-9]+)(,[0-9][0-9][0-9])*([.][0-9]){0,1}([0-9]*)$/" ,$value) == 1;
    $world = preg_match ("/^(-){0,1}([0-9]+)(.[0-9][0-9][0-9])*([,][0-9]){0,1}([0-9]*)$/" ,$value) == 1;
   return ($american or $world);
}
?>

-the English/American way of writing a float million number: 1,000,000.00
-the global way of writing a float million number: 1.000.000,02

kendsnyder at gmail dot com (29-Jun-2007 06:49)

Be careful when using is_numeric() to escape SQL strings.  is_numeric('0123') returns true but 0123 without quotes cannot be inserted into SQL.  PHP interprets 0123 without quotes as a literal octal number; but SQL just throws a syntax error.

<?php
is_numeric('0123'); // true
is_numeric(0.123); // true
is_numeric('0.123'); // true
is_numeric(123); // true
is_numeric('123'); // true
is_numeric('foo'); // false
?>

Casting a value to float then string and comparing it to the original value cast as string as the same effect as is_numeric but returns false for numeric strings that begin with zero and have no decimal point.  Examples:
<?php
function isDecimalNumber($n) {
  return (string)(float)$n === (string)$n;
}

isDecimalNumber('0123'); // false
isDecimalNumber(0.123); // true
isDecimalNumber('0.123'); // true
isDecimalNumber(123); // true
isDecimalNumber('123'); // true
isDecimalNumber('foo'); // true

?>

Carlos Madeira (02-Jun-2007 06:46)

If I may, i think there is a simpler way to determine if a number is odd or even:

if( $number & 1 ) //Just check the last bit!
  echo 'It's odd!';
else
  echo 'It's even!';

Kenn (11-May-2007 07:45)

A side note, finding out if an integer is even or odd, given the integer = $i ...

if (($i % 2) == 0) // This will test TRUE if the integer is even.
   {
xxx insert code here xxx
   }

Q1712 at online dot ms (24-Apr-2007 09:33)

a regex doing the same as is_numeric() is:
"^((-?[0-9]*\.[0-9]+|[[:space:]]*[+-]?[0-9]+(\.[0-9]*)?)
([eE][+-]?[0-9]+)?|0x[0-9a-fA-F]+)$" (took me some testing to figure this out)
regex: "^(decimal|hex)$"
  decimal: "(base1|base2)(exponent)?"
    base1: "-?[0-9]*\.[0-9]+"
           if there are no prepanded spaces and no "+" the
           base may be any of "0", ".0", "0.0".
    base2: "[[:space:]]*[+-]?[0-9]+(\.[0-9]*)?"
           if there are empty spaces or a "+" prepanded the
           base may only be "0" or "0.0" (no idea why)
    exponent: "[eE][+-]?[0-9]+"
              the exponent is opional
  hex: "0x[0-9a-fA-F]+"
usage: preg_match("/regex/D", $str); or ereg("regex", $str);

Just to know what is_numeric() is doing. Of cause the regex should be much slower and is_numeric() also returns false if the number would be to big to fit into a double.

Elwin van Huissteden (27-Mar-2007 12:05)

To James holwell:

Maybe your function was more strickt, but profides FALSE to any numeric string that wasnt written in the English/American notition. To enable a person to use the both the English/American and the rest of the world's way:

<?php
  function my_is_numeric($value)
  {
   return (preg_match ("/\A(-){0, 1}([0-9]+)((,|.)[0-9]{3, 3})*((,|.)[0-9]){0, 1}([0-9]*)\z/" ,$value) == 1);
  }
?>

Other than that, i'd recommend using yours, if it works (i havent tested either yours or mine)
By using mine, there might be a slight chance to not being able to do calculations with the numeric string if it's not the English/American way.

(*Note:
-the E/A way of writing 1 million (with decimal for 1/50): 1,000,000.02
-the global way of writing 1 million (with decimal for 1/50): 1.000.000,02

james.holwell( at )exeter.ox.ac.uk (20-Mar-2007 10:07)

In reply to www.kigoobe.com, a more strict expression is

<?php
  function my_is_numeric($value)
  {
    return (preg_match ("/^(-){0,1}([0-9]+)(,[0-9][0-9][0-9])*([.][0-9]){0,1}([0-9]*)$/", $value) == 1);
  }
?>

This will not match strings like -6,77.8,8 which are matched by the below expression, and instead requires a single decimal point, with at least one character following, and only permits comma-separation when the right hand side is a triplet.

Stephen (25-Jan-2007 05:31)

The documentation is not completely precise here. is_numeric will also return true if the number begins with a decimal point  and/or a space, provided a number follows (rather than a letter or punctuation). So, it doesn't necessarily have to start with a digit.

mariusads::at::helpedia.com (19-Jan-2007 09:56)

Test if a number is positive and contains only 0-9:

function is_number($number)
{
    $text = (string)$number;
    $textlen = strlen($text);
    if ($textlen==0) return 0;
    for ($i=0;$i < $textlen;$i++)
    { $ch = ord($text{$i});
       if (($ch<48) || ($ch>57)) return 0;
    }
    return 1;
}

returns

0 : number contain character outside 0-9
1 : valid number.

meagar at gmail dot com (14-Jan-2007 03:52)

Miero: Your function doesn't match some special cases: '+1', '-0', '+0', all of which are valid integers.  The easiest and most reliable way to get a definite integer match is with a regular expression:

function is_intval($value) {
     return 1 === preg_match('/^[+-]?[0-9]+$/', $value);
}

This has two "problems" based on your input:  it matches both '00' and '999999999999999999999999999999999' as valid integers.

I'm not sure why you wouldn't want to match "00".  Regardless of whether somebody entered it in a form by accident or on purpose, it /is/ a valid integer, and in most instances you should accept it.

The second value, "999..." is also a valid integer, even if PHPs internal int type isn't precise enough to represent it.

alexander dot j dot summers at imperial dot ac dot uk (23-Oct-2006 05:05)

Note that the even simpler functions for checking if a variable contains an odd or even number below don't produce good results if you apply them to arguments which aren't numeric; I guess that was the idea of the originals.

e.g. using the functions defined in two posts below..

IS_ODD(null)  returns false
IS_EVEN(null) returns true
is_odd(null)    returns false
is_even(null)  returns false

ja at krystof dot org (02-Sep-2006 02:10)

Here is a simple function to recognize whether the value is a natural number: (Zero is often exclude from the natural numbers, that's why there's the second parameter.)

<?php
function is_natural($val, $acceptzero = false) {
 $return = ((string)$val === (string)(int)$val);
 if ($acceptzero)
  $base = 0;
 else
  $base = 1;
 if ($return && intval($val) < $base)
  $return = false;
 return $return;
}
?>

moskalyuk at gmail dot com (21-Aug-2006 06:18)

is_numeric fails on the hex values greater than LONG_MAX, so having a large hex value parsed through is_numeric would result in FALSE being returned even though the value is a valid hex number

rontarrant at NO_SPAMsympatico dot ca (24-Jul-2006 03:15)

Here's an even simpler pair of functions for finding out if a number is odd or even:

function IS_ODD($number) { return($number & 1); }

function IS_EVEN($number) { return(!($number & 1)); }

Test:
$myNumber = 151;

if(IS_ODD($myNumber))
    echo("number is odd\n");
else
    echo("number is NOT odd\n");

if(IS_even($myNumber))
    echo("number is even\n");
else
    echo("number is NOT even\n");

Results:
number is odd
number is NOT even

Miero (08-Jul-2006 05:31)

function is_intval($a) {
    return ((string)$a === (string)(int)$a);
}

true for ("123", "0", "-1", 0, 11, 9011, 00, 0x12, true)
false for (" ", "", 1.1, "123.1", "00", "0x123", "123a", "ada", "--1", "999999999999999999999999999999999", false, null, '1 ')

andrea dot vacondio at gmail dot com (13-Dec-2005 03:52)

Two simple functions using is_numeric:

<?php

 function is_odd($num){
     return (is_numeric($num)&($num&1));
 }
 
 function is_even($num){
     return (is_numeric($num)&(!($num&1)));
 }

 //examples
echo "1: odd? ".(is_odd(1)? "TRUE": "FALSE")."<br />";
//is_numeric(0) returns true
echo "0: odd? ".(is_odd(0)? "TRUE": "FALSE")."<br />";
echo "6: odd? ".(is_odd(6)? "TRUE": "FALSE")."<br />";
echo "\"italy\": odd? ".(is_odd("italy")? "TRUE": "FALSE")."<br />";
echo "null: odd? ".(is_odd(null)? "TRUE": "FALSE")."<br /><br />";
echo "1: even? ".(is_even(1)? "TRUE": "FALSE")."<br />"; 
echo "0: even? ".(is_even(0)? "TRUE": "FALSE")."<br />";
echo "6: even? ".(is_even(6)? "TRUE": "FALSE")."<br />";
echo "\"italy\": even? ".(is_even("italy")? "TRUE": "FALSE")."<br />"; 
echo "null: even? ".(is_even(null)? "TRUE": "FALSE")."<br />";

?>
And here is the result:
1: odd? TRUE
0: odd? FALSE
6: odd? FALSE
"italy": odd? FALSE
null: odd? FALSE

1: even? FALSE
0: even? TRUE
6: even? TRUE
"italy": even? FALSE
null: even? FALSE

jamespam at hotmail dot com (08-Aug-2005 10:31)

Here's a function to determine if a variable represents a whole number:

function is_whole_number($var){
  return (is_numeric($var)&&(intval($var)==floatval($var)));
}

just simple stuff...
is_whole_number(2.00000000001); will return false
is_whole_number(2.00000000000); will return true

namik at hub-cafe dot net (30-Jul-2005 02:11)

I needed a number_suffix function that takes numbers with thousand seperators (using number_format() function).  Note that this doesn't properly handle decimals.

Example:
<?= number_suffix('1,021') ?> returns: 1,021st

Also, increasing the range above the condition statements increases efficiency.  That's almost 20% of the numbers between 0 and 100 that get to end early.

<?
  function number_suffix($number)
  {
    // Validate and translate our input
    if ( is_numeric($number) )
    {
      // Get the last two digits (only once)
      $n = $number % 100;
    } else {
     // If the last two characters are numbers
     if ( preg_match( '/[0-9]?[0-9]$/', $number, $matches ) )
     {
       // Return the last one or two digits
       $n = array_pop($matches);
     } else {
       // Return the string, we can add a suffix to it
       return $number;
     }
    }
    // Skip the switch for as many numbers as possible.
    if ( $n > 3 && $n < 21 )
      return $number . 'th';

    // Determine the suffix for numbers ending in 1, 2 or 3, otherwise add a 'th'
    switch ( $n % 10 )
    {
      case '1': return $number . 'st';
      case '2': return $number . 'nd';
      case '3': return $number . 'rd';
      default:  return $number . 'th';
    }
  }
?>

maninblack00 at mail dot ru (30-Jul-2005 12:23)

blazatek at wp dot pl wrote a function to check POST inputs for ASCII-keys or smth like that. there was an error while filtering $varvalue (it was only the value of the last filter 'addslashes')

here's the corrected function:
<?

function is_num ($num) {
      // .....
}

function test_post($tab) {
   $post = array();
   $post = $tab;
   foreach ($post as $varname => $varvalue) {
       echo $tab[$varname];
       if (empty($varvalue)) {
                 $post[$varname] = null;
       }
       elseif (is_num($varvalue)) {
                 $varvalue=trim($varvalue);
                 $varvalue=strip_tags($varvalue);   
                 $varvalue=intval($varvalue);
                 $post[$varname]=addslashes($varvalue);   
       }
       else {   
                 $post[$varname]=NULL;
       }
   }//forech   
    return $post;
}
?>

hope that correction is correct ;)

sebu (28-Jul-2005 12:37)

Referring to previous post "Be aware if you use is_numeric() or is_float() after using set_locale(LC_ALL,'lang') or set_locale(LC_NUMERIC,'lang')":

This is totally wrong!

This was the example code:

-----
  set_locale(LC_NUMERIC,'fr');
  is_numeric(12.25); // Return False
  is_numeric(12,25); // Return True
  is_float(12.25); //Return False
  is_float(12,25); //Return True
-----

This is nonsense!

- set_locale() does not exist, you must use setlocale() instead
- you have to enclose 12,25 with quotes; otherwise PHP will think that
the function gets _two_ arguments: 12 and 25 (depending on PHP version and setup you may additionally get a PHP warning)
- if you don't enclose 12,25 with quotes the first argument will be the inspected value (12), the second value (25) is discarded. And is_numeric(12) and is_float(12) is always TRUE

Corrected Example:

----
  setlocale(LC_NUMERIC,'fr');
  is_numeric(12.25); // Return True
  is_numeric("12,25"); // Return False
  is_float(12.25); //Return True
  is_float("12,25"); //Return False
----

Remarks:
- is_float(12.25) is _always_ TRUE, 12.25 is a PHP language construct (a "value") and the way PHP interpretes files is definitely _not_ affected by the locale
- is_float("12,25") is _always_ FALSE, since is_float (other than is_numeric): if the argument is a string then is_float() always returns FALSE since it does a strict check for floats

And the corrected example shows: you get the _same_ results for every possible locale, is_numeric() does not depend on the locale.

ishmaelmakitla at yahoo dot com (20-May-2005 01:05)

//hello mates I just wanted to bring this forth so that you may see what I have been to
I tried to validate a certain field (name ) on my project web site design so that the only field acceptable is alphabetic the problem was that it has to include a space as in "Makitla M.I"
now ctype_alpha returned false as this includes a space
the same with
<?
  if(!ctype_alpha($name)||!ctype_space($name))
?>

now this is what I did
<?
    $name=explode(" ",$name);//to get rid of space charecter
   $name=explode(".",$name)//to get rid of the dod
//finally I tested if the resulting $name is purely alphabetic
if(!ctype_alpha($name))
     {
        echo"the name entered contained some   unacceptable       charecters...please reenter";
     exit;
    }
//this solved my problem...hope this helps some of you!!
?>

Gregory Boshoff (14-May-2005 11:01)

As mentioned above use the ctype character type functions to determine a strings type as ctype is faster. ctype_digit has far better benchmarks than is_numeric.

// Example:
$num = '888';
if(ctype_digit($num) === TRUE):
echo 'The string variable $num contains the decimal value '.$num;
endif;

Titouthat (27-Apr-2005 08:47)

This function converts an input string into bool, int or float depending on its content.

<?php
function convert_type( $var )
{
    if( is_numeric( $var ) )
    {
        if( (float)$var != (int)$var )
        {
            return (float)$var;
        }
        else
        {
            return (int)$var;
        }
    }
   
    if( $var == "true" )    return true;
    if( $var == "false" )    return false;
   
    return $var;
}
?>

'90' return an int
'90.9' return a float
'true' return a bool
'90.0' return a int

lukesneeringer at gmail dot com (19-Mar-2005 04:32)

Regarding renimar at yahoo's function to yield ordinal numbers, the function lacks one thing. It accounts for numbers in the teens only if the number is below 100. If you used this function and gave 212 as the input, it would give 212nd, and not 212th. (Also, checking for numbers between 11 and 13 is sufficient, since 14-19 yield th either way.)

Therefore,
<?php if ($num >= 11 and $num <= 19) ?>
should be changed to...
<?php if ($num % 100>= 11 and $num % 100 <= 13) ?>

It will then work perfectly all the time.

Here's the entire function with the one line changed:
<?php
function ordinalize($num) {
       if (!is_numeric($num))
               return $num;

       if ($num % 100 >= 11 and $num % 100 <= 13)
               return $num."th";
       elseif ( $num % 10 == 1 )
               return $num."st";
       elseif ( $num % 10 == 2 )
               return $num."nd";
       elseif ( $num % 10 == 3 )
               return $num."rd";
       else // $num % 10 == 0, 4-9
               return $num."th";
}
?>

codeslinger at compsalot dot com (18-Feb-2005 05:00)

in version 4.3.10  I find the following

".73"  TRUE
"0.73"  TRUE
"+0.73"  TRUE

"+.73"   FALSE

I would not call it a bug, just something to be aware of.

-----

Also be aware that if you give php a huge number and then you convert it to a string you get  

"INF"

if you pass that to mySQL etc. you could have a problem...

mdallaire at virtuelcom dot com (18-Nov-2004 12:23)

Sometimes, we need to have no letters in the number and is_numeric does not quit the job.
You can try it this ways to make sure of the number format:

    function new_is_unsigned_float($val) {
        $val=str_replace(" ","",trim($val));
        return eregi("^([0-9])+([\.|,]([0-9])*)?$",$val);
    }

    function new_is_unsigned_integer($val) {
        $val=str_replace(" ","",trim($val));
        return eregi("^([0-9])+$",$val);
    }

    function new_is_signed_float($val) {
        $val=str_replace(" ","",trim($val));
        return eregi("^-?([0-9])+([\.|,]([0-9])*)?$",$val);
    }

    function new_is_signed_integer($val) {
        $val=str_replace(" ","",trim($val));
        return eregi("^-?([0-9])+$",$val);
    }

It returns 1 if okay and returns nothing "" if it's bad number formating.

php at thefriedmans dot net (13-Oct-2004 06:19)

is_numeric() in php5 returns false for strings with a leading decimal point:

<?php
is_numeric('5'); // true
is_numeric('5.5'); // true
is_numeric('.5'); // false

// but...

is_numeric('.0.5'); // true
?>

In certain situations, it may be useful to prepend a '0' to the string you're verifying with is_numeric():

<?php
if (is_numeric('0' . $user_input)) // ...
?>

renimar no spam at nospam yahoo dot com (03-May-2004 08:54)

A little function to ordinalize numbers using is_numeric() and accounting for the numbers in the teens.

<?php
function ordinalize($num) {

        if (!is_numeric($num))
                return $num;

        if ($num >= 11 and $num <= 19)
                return $num."th";
        elseif ( $num % 10 == 1 )
                return $num."st";
        elseif ( $num % 10 == 2 )
                return $num."nd";
        elseif ( $num % 10 == 3 )
                return $num."rd";
        else
                return $num."th";

}

// Demo
for ($i=1; $i<=25; $i++) {
        print ordinalize($i) . " ";
}

// The loop returns:
// 1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th
// 13th 14th 15th 16th 17th 18th 19th 20th 21st 22nd
// 23rd 24th 25th

?>

joe at kewlmail dot net (16-Jan-2004 11:12)

Here is a simple function that I found usefull for filtering user input into numbers. Basically, it attempts to fix fat fingering. For example:

$userString = "$654.4r5";

function numpass_filter($userString){ 
    $money = explode(".", $userString);
    //now $money[0] = "$645" and $money[1] = "4r5"

    //next remove all characters save 0 though 9
    //in both elements of the array
    $dollars = eregi_replace("[^0-9]", null, $money[0]);
    $cents = eregi_replace("[^0-9]", null, $money[1]);

    //if there was a decimal in the original string, put it back
    if((string)$cents!=null){
        $cents = "." . $cents;
    }

   $result = $dollars . $cents;

    return($result);
}

The output in this case would be '654.45'.
Please note that this function will work properly unless the user fat fingers an extra decimal in the wrong place.

kouber at saparev dot com (24-Nov-2003 11:05)

Note that this function is not appropriate to check if "is_numeric" for very long strings. In fact, everything passed to this function is converted to long and then to a double. Anything greater than approximately 1.8e308 is too large for a double, so it becomes infinity, i.e. FALSE. What that means is that, for each string with more than 308 characters, is_numeric() will return FALSE, even if all chars are digits.

However, this behaviour is platform-specific.

http://www.php.net/manual/en/language.types.float.php

In such a case, it is suitable to use regular expressions:

function is_numeric_big($s=0) {
  return preg_match('/^-?\d+$/', $s);
}

blazatek at wp dot pl (21-Oct-2003 04:05)

the best way to check whether
variable is numeric is to check its ascii code :)

function is_num($var)
{
    for ($i=0;$i<strlen($var);$i++)
    {
        $ascii_code=ord($var[$i]);
       
        if ($ascii_code >=49 && $asci_code <=57)
            continue;
        else
            return false;
    }
   
        return true;
}
this function can be usefull if you wont to chec eg $_POST

function test_post($tab)
{
       
        $post = array();
        $post=$tab;
        echo $tab["user_name"];
        foreach ($post as $varname => $varvalue)
        {
        if (empty($varvalue))
        {
            $post[$varname] = null;
      
        }elseif (is_num($varvalue))
        {
                        $post[$varname]=trim($varvalue);
    $post[$varname]=strip_tags($varvalue);   
    $post[$varname]=intval($varvalue);
    $post[$varname]=addslashes($varvalue);   
    }else
    {   
                  $post[$varname]=NULL;
    }
            }
        }//forech    
    return $post;
}

stew_wilde at hotmail dot com (07-Aug-2003 09:25)

When using the exec() function in php to execute anther php script, any command line arguments passed the script will lose their type association, regardless of whether they are numeric or not, the same seems to hold true for strings as well.

ie : two scripts test.php:

<?php
$val = trim($argv[1]);
echo is_string($val);
?>

and testwrapper.php:

<?php
$tmp = 5;
exec("php ./test.php ".$tmp);
?>

Executing testwrapper.php on the command line will echo nothing (ie false), and false will be returned regardless of any escaping of parameters or other such attempts to overcome this.  The solution then is to explicitly cast $val in test.php to be an int and then is_numeric will work.  But as stated the same test was performed using a string for $val and the is_string() function and the same thing occurs.  Not the end of the world, but something to be aware of :)

andi_nrw at hotmail dot com (12-Feb-2003 04:25)

<?php
/* This function is not useful if you want
to check that someone has filled in only
numbers into a form because for example
4e4 and 444 are both "numeric".

I used a regular expression for this problem
and it works pretty good. Maybe it is a good
idea to write a function and then to use it.

$input_number = "444"; // Answer 1
$input_number = "44 "; // Answer 2
$input_number = "4 4"; // Answer 2
$input_number = "4e4"; // Answer 2
$input_number = "e44"; // Answer 2
$input_number = "e4e"; // Answer 2
$input_number = "abc"; // Answer 2
*/
$input_number = "444";

if (preg_match ("/^([0-9]+)$/", $input_number)) {
     print "Answer 1";
} else {
     print "Answer 2";
}
?>

php dot net at davidmcarthur dot com (17-Jan-2003 08:02)

This is a little more explicit and won't break when the value can't be legally cast as an int

function is_intValued($var)
{
    // Determines if a variable's value is an integer regardless of type
    // meant to be an analogy to PHP's is_numeric()
    if (is_int($var)) return TRUE;
    if (is_string($var) and $var === (string)(int) $var) return TRUE;
    if (is_float($var) and $var === (float)(int) $var) return TRUE;
    else return FALSE;
}

redy dot r at madagascan dot com (11-Dec-2002 12:54)

Be aware if you use is_numeric() or is_float() after using set_locale(LC_ALL,'lang') or set_locale(LC_NUMERIC,'lang')

Example :
If at the beginning of your script, you declare :

<?php
set_locale(LC_NUMERIC,'fr');
?>

and after, you will get this :

<?php
is_numeric(12.25); // Return False
is_numeric(12,25); // Return True
is_float(12.25); //Return False
is_float(12,25); //Return True
?>

Because, for french language the decimal separator is ',' (Comma) instead of '.' (Dot).

martijnt at dataserve dot nl (02-Dec-2002 01:21)

If you want to make sure that a variable contains only one or more numbers as in the range 0-9, you could use this:

eregi("[^0-9]",$var)

This checks your variable for anything that is NOT in the range 0-9.

If you use is_numeric() while checking an IP address, you should not be surprised if the following is accepted as a valid IP: 1e13.3.4.12e3 -> is_numeric() considers 1e13 and 12e3 as valid numeric values (which is correct).

Have fun.

Martijn Tigchelaar,
DataServe.

eagleflyer2 at lycos dot com (06-Sep-2002 09:02)

Hi !
Many of you may have experienced that the 'is_numeric' function seems to fail always when form entries are checked against their variable type. So the function seems to return  'false' even if the form entry was aparently a number or numeric string.

The solution is pretty simple and no subroutines or fancy operations are necessary to make the 'is_numeric' function usable for form entry checks:

Simply strip off all (invisible) characters that may be sent along with the value when submitting a form entry.

Just use the 'trim' function before 'is_numeric'.

Example:

$variable = trim($variable);
if (is_numeric($variable)
{...#do something#...}
else
{...#do something else#...}

mjbraca at NOSPAM dot hotmail dot com (24-Oct-2001 06:36)

Some examples. Note that leading white space is OK, but not trailing white space, and there can't be white space between the "-" and the number.

is_numeric("1,000") = F
is_numeric("1e2")   = T
is_numeric("-1e-2") = T
is_numeric("1e2.3") = F
is_numeric("1.")    = T
is_numeric("1.2")   = T
is_numeric("1.2.3") = F
is_numeric("-1")    = T
is_numeric("- 1")   = F
is_numeric("--1")   = F
is_numeric("1-")    = F
is_numeric("1A")    = F
is_numeric(" 1")    = T
is_numeric("1 ")    = F

tvali at email dot ee (10-Oct-2001 08:53)

I changed function sent by
"ealma@hotmail.com 18-May-2001 12:02"
a little bit (it should be faster now).

Here is some code that will detect large values for numeric and for PHP3.

function is_num($s) {
  for ($i=0; $i<strlen($s); $i++) {
    if (($s[$i]<'0') or ($s[$i]>'9')) {return false;}
  }
return true;
}

You can also check only the first char in string (($s[0])<'9')and($s[0]>'0')), since php converts string to numeric only from beginning to the last digit.

aulbach at unter dot franken dot de (17-Sep-2001 07:07)

If you want to check, if a string will be converted into the exactly same number, you have to test the following:

if ( (string)(int)$val === (string)$val ) ...

This is not the same as

if ( is_numeric($val) ) ...

cause

<?php

$a="0000001";
if ( is_numeric($a) ) echo "a is numeric";
if ( (string)(float)$a !== (string)$a) echo "a cannot be converted 100%-correctly";
?>

will output:
a is numeric
a cannot be converted 100%-correctly

Ok, ok, I know. This is a hysteric type-check. It depends on the type of application, if you use it. The aim should always be, that the user could be warned, if the value cannot be stored in the way, the user types it into.

Why? Therefore is the following example:
If you set
$a="1E+17";
the above script says that it is all right.

But then we want to convert to INT, not FLOAT. is_numeric() doesn't distinct between INT and FLOAT, so a is_numeric('1E+17') is true, but the Integer of it returns 1, which isn't perhaps, what the user expects.