is_numeric
Проверяет, является ли данная переменная числом. Строки, содержащие числа, состоят из необязательного знака, любого количества цифр, необязательной десятичной части и необязательной экспоненциальной части. Так, +0123.45e6 является верным числовым значением. Шестнадцатеричная (0xFF), двоичная (0b10100111001) и восьмеричная (0777) записи также допускаются, но только без знака, десятичной и экспоненциальной части.
Список параметров
Возвращаемые значения
Возвращает TRUE , если var является числом или строкой, содержащей число, в противном случае возвращается FALSE .
Примеры
Пример #1 Примеры использования is_numeric()
$tests = array(
«42» ,
1337 ,
0x539 ,
02471 ,
0b10100111001 ,
1337e0 ,
«not numeric» ,
array(),
9.1
);
foreach ( $tests as $element ) if ( is_numeric ( $element )) echo «‘ < $element >‘ — число» , PHP_EOL ;
> else echo «‘ < $element >‘ — НЕ число» , PHP_EOL ;
>
>
?>
Результат выполнения данного примера:
'42' - число '1337' - число '1337' - число '1337' - число '1337' - число '1337' - число 'not numeric' - НЕ число 'Array' - НЕ число '9.1' - число
Смотрите также
- ctype_digit() — Проверяет на наличие цифровых символов в строке
- is_bool() — Проверяет, является ли переменная булевой
- is_null() — Проверяет, является ли значение переменной равным NULL
- is_float() — Проверяет, является ли переменная числом с плавающей точкой
- is_int() — Проверяет, является ли переменная переменной целочисленного типа
- is_string() — Проверяет, является ли переменная строкой
- is_object() — Проверяет, является ли переменная объектом
- is_array() — Определяет, является ли переменная массивом
is_numeric
Determines if the given variable is a number or a numeric string.
Parameters
The variable being evaluated.
Return Values
Returns true if value is a number or a numeric string, false otherwise.
Changelog
| Version | Description |
|---|---|
| 8.0.0 | Numeric strings ending with whitespace ( «42 » ) will now return true . Previously, false was returned instead. |
Examples
Example #1 is_numeric() examples
$tests = array(
«42» ,
1337 ,
0x539 ,
02471 ,
0b10100111001 ,
1337e0 ,
«0x539» ,
«02471» ,
«0b10100111001» ,
«1337e0» ,
«not numeric» ,
array(),
9.1 ,
null ,
» ,
);
foreach ( $tests as $element ) if ( is_numeric ( $element )) echo var_export ( $element , true ) . » is numeric» , PHP_EOL ;
> else echo var_export ( $element , true ) . » 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 1337.0 is numeric '0x539' is NOT numeric '02471' is numeric '0b10100111001' is NOT numeric '1337e0' is numeric 'not numeric' is NOT numeric array ( ) is NOT numeric 9.1 is numeric NULL is NOT numeric '' is NOT numeric
Example #2 is_numeric() with whitespace
$tests = [
» 42″ ,
«42 » ,
«\u9001» , // non-breaking space
«9001\u» , // non-breaking space
];
foreach ( $tests as $element ) if ( is_numeric ( $element )) echo var_export ( $element , true ) . » is numeric» , PHP_EOL ;
> else echo var_export ( $element , true ) . » is NOT numeric» , PHP_EOL ;
>
>
?>
Output of the above example in PHP 8:
' 42' is numeric '42 ' is numeric ' 9001' is NOT numeric '9001 ' is NOT numeric
Output of the above example in PHP 7:
' 42' is numeric '42 ' is NOT numeric ' 9001' is NOT numeric '9001 ' is NOT numeric
See Also
- Numeric strings
- 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
- filter_var() — Filters a variable with a specified filter
User Contributed Notes 8 notes
Note that the function accepts extremely big numbers and correctly evaluates them.
$v = is_numeric ( ‘58635272821786587286382824657568871098287278276543219876543’ ) ? true : false ;
var_dump ( $v );
?>
The above script will output:
So this function is not intimidated by super-big numbers. I hope this helps someone.
PS: Also note that if you write is_numeric (45thg), this will generate a parse error (since the parameter is not enclosed between apostrophes or double quotes). Keep this in mind when you use this function.
for strings, it return true only if float number has a dot
is_numeric( ‘42.1’ )//true
is_numeric( ‘42,1’ )//false
Apparently NAN (Not A Number) is a number for the sake of is_numeric().
echo «is » ;
if (! is_numeric ( NAN ))
echo «not » ;
echo «a number» ;
?>
Outputs «is a number». So something that is NOT a number (by defintion) is a number.
is_numeric fails on the hex values greater than LONG_MAX, so having a large hex value parsed through is_numeric would result in FALSE being returned even though the value is a valid hex number
is incorrect for PHP8, it’s numeric.
Note that this function is not appropriate to check if «is_numeric» for very long strings. In fact, everything passed to this function is converted to long and then to a double. Anything greater than approximately 1.8e308 is too large for a double, so it becomes infinity, i.e. FALSE. What that means is that, for each string with more than 308 characters, is_numeric() will return FALSE, even if all chars are digits.
However, this behaviour is platform-specific.
In such a case, it is suitable to use regular expressions:
function is_numeric_big($s=0) return preg_match(‘/^-?\d+$/’, $s);
>
Note that is_numeric() will evaluate to false for number strings using decimal commas.
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).
$eng_or_world = preg_match
( ‘/^[+-]?’ . // start marker and sign prefix
‘((((8+)|(1(,8)+)))?(\\.3)?(3*)|’ . // american
‘(((2+)|(8(\\.3)+)))?(,8)?(4*))’ . // world
‘(e2+)?’ . // exponent
‘$/’ , // 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.
PHP : is_double() function
The is_double () function is used to test whether a variable is a float or not. The function is an alias of is_float().
*Mixed : Mixed indicates that a parameter may accept multiple (but not necessarily all) types.
Return value:
TRUE if var_name is a float, FALSE otherwise.
Value Type: Boolean.
'; else echo 'This is not a double value.
'; echo '
'; var_dump(is_double(85)); echo '
'; var_dump(is_double(1e8)); echo '
'; var_dump(is_double(true)); echo '
'; var_dump(is_double(array(23.3, 56, 6))); ?> This is a double value. bool(false) bool(true) bool(false) bool(false)
Practice here online :
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