is_numeric

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.

for strings, it return true only if float number has a dotis_numeric( '42.1' )//trueis_numeric( '42,1' )//false

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

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...

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.

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.phpIn such a case, it is suitable to use regular expressions:function is_numeric_big($s=0) {  return preg_match('/^-?\d+$/', $s);}

These functions are designed for precise number type validation:isInteger checks if a value is an integer (including string representations of integers).isFloat verifies if a value is a floating-point number (including string representations of decimals).They handle all number formats (positive, negative, leading zeros, dots at start/end) while rejecting non-numeric values (booleans, arrays, null).<?php    function isInteger(mixed $val): bool    {        if (!is_scalar($val) || is_bool($val)) {            return false;        }        if (is_int($val)) {            return true;        }        if (isFloat($val)) {            return false;        }        return preg_match('~^((?:\+|-)?[0-9]+)$~', (string) $val) === 1;    }    function isFloat(mixed $val): bool    {        if (!is_scalar($val) || is_bool($val)) {            return false;        }        if (gettype($val) === "double") {            return true;        }        if (!is_string($val)) {            return false;        }        return preg_match('/^[+-]?(\d*\.\d+|\d+\.\d*)$/', $val) === 1;    }    $testValues = [        // Integers        42,                      // integer        '42',                    // string integer        '+42',                   // string with plus        '-42',                   // string with minus        '0042',                  // leading zeros        '000',                   // zeros        PHP_INT_MAX,             // maximum int        (string) PHP_INT_MAX,    // maximum int as string        // Floating point numbers        3.14,                    // float        '3.14',                  // string float        '.5',                    // without integer part        '5.',                    // without fractional part        '0.5',                   // with zero integer part        '5.0',                   // with zero fractional part        '+3.14',                 // with plus        '-3.14',                 // with minus        '0.0',                   // zero float        '00.5',                  // leading zeros in integer part        '5.00',                  // leading zeros in fractional part        '-.5',                   // negative without integer part        '-5.',                   // negative without fractional part        // Non-numbers        null,                    // null        [],                      // array        true,                    // boolean true        false,                   // boolean false        'string',                // regular string        '123abc',                // number with letters        '12.3.4',                // multiple dots        '++12',                  // double plus        '--12',                  // double minus        '12 ',                   // trailing space        ' 12',                   // leading space        '',                      // empty string        '1e5',                   // exponential notation        1e5,                     // float in exponential form    ];    foreach ($testValues as $value) {        $display = match (true) {            is_null($value) => 'null',            is_array($value) => '[]',            is_bool($value) => $value ? 'true' : 'false',            default => $value        };        $type = gettype($value);        echo "$display: $type";        echo " | isInteger: " . (isInteger($value) ? 'yes' : 'no');        echo " | isFloat: " . (isFloat($value) ? 'yes' : 'no');        echo PHP_EOL;    }?>

Note that is_numeric() will evaluate to false for number strings using decimal commas.is_numeric('0.11');Output: trueis_numeric('0,11');Output: false