is_numeric

(PHP 4, PHP 5)

is_numeric Finds whether a variable is a number or a numeric string

Description

bool is_numeric ( mixed $var )

Finds whether the given variable is numeric. Numeric strings consist of optional sign, any number of digits, optional decimal part and optional exponential part. Thus +0123.45e6 is a valid numeric value. Hexadecimal (e.g. 0xf4c3b00c), Binary (e.g. 0b10100111001), Octal (e.g. 0777) notation is allowed too but only without sign, decimal and exponential part.

Parameters

var

The variable being evaluated.

Return Values

Returns TRUE if var is a number or a numeric string, FALSE otherwise.

Examples

Example #1 is_numeric() examples

<?php
$tests 
= array(
    
"42",
    
1337,
    
0x539,
    
02471,
    
0b10100111001,
    
1337e0,
    
"not numeric",
    array(),
    
9.1
);

foreach (
$tests as $element) {
    if (
is_numeric($element)) {
        echo 
"'{$element}' is numeric"PHP_EOL;
    } else {
        echo 
"'{$element}' is NOT numeric"PHP_EOL;
    }
}
?>

The above example will output:

'42' is numeric
'1337' is numeric
'1337' is numeric
'1337' is numeric
'1337' is numeric
'1337' is numeric
'not numeric' is NOT numeric
'Array' is NOT numeric
'9.1' is numeric

See Also

  • ctype_digit() - Check for numeric character(s)
  • is_bool() - Finds out whether a variable is a boolean
  • is_null() - Finds whether a variable is NULL
  • is_float() - Finds whether the type of a variable is float
  • is_int() - Find whether the type of a variable is integer
  • is_string() - Find whether the type of a variable is string
  • is_object() - Finds whether a variable is an object
  • is_array() - Finds whether a variable is an array

Коментарии

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.

language.types.float

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

function is_numeric_big($s=0) {
  return preg_match('/^-?\d+$/', $s);
}
2003-11-24 05:05:11
http://php5.kiev.ua/manual/ru/function.is-numeric.html
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
2006-08-21 13:18:16
http://php5.kiev.ua/manual/ru/function.is-numeric.html
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.
2009-01-07 08:01:40
http://php5.kiev.ua/manual/ru/function.is-numeric.html
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.
2011-01-22 17:55:26
http://php5.kiev.ua/manual/ru/function.is-numeric.html
Apparently NAN (Not A Number) is a number for the sake of is_numeric(). 

<?php 
echo "is "
if (!
is_numeric(NAN)) 
 echo 
"not "
 echo 
"a number"
?> 

Outputs "is a number". So something that is NOT a number (by defintion) is a number...
2014-01-08 01:20:43
http://php5.kiev.ua/manual/ru/function.is-numeric.html
for strings, it return true only if float number has a dot

is_numeric( '42.1' )//true
is_numeric( '42,1' )//false
2017-02-03 17:22:09
http://php5.kiev.ua/manual/ru/function.is-numeric.html
Example #2

Output: 

'9001 ' is NOT numeric

is incorrect for PHP8, it's numeric.

So please correct this.
2022-08-22 08:16:50
http://php5.kiev.ua/manual/ru/function.is-numeric.html
Автор:
Note that is_numeric() will evaluate to false for number strings using decimal commas.

is_numeric('0.11');
Output: true

is_numeric('0,11');
Output: false
2022-12-07 10:44:55
http://php5.kiev.ua/manual/ru/function.is-numeric.html

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