Ctype 函数
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ctype_digit

(PHP 4 >= 4.0.4, PHP 5)

ctype_digit — Check for numeric character(s)

说明

bool ctype_digit ( string $text )

Checks if all of the characters in the provided string, text, are numerical.

参数

text

The tested string.

返回值

Returns TRUE if every character in the string text is a decimal digit, FALSE otherwise.

更新日志

版本 说明
5.1.0 Before PHP 5.1.0, this function returned TRUE when text was an empty string.

范例

Example #1 A ctype_digit() example

<?php
$strings = array('1820.20', '10002', 'wsl!12');
foreach ($strings as $testcase) {
    if (ctype_digit($testcase)) {
        echo "The string $testcase consists of all digits.\n";
    } else {
        echo "The string $testcase does not consist of all digits.\n";
    }
}
?>

以上例程会输出：

The string 1820.20 does not consist of all digits.
The string 10002 consists of all digits.
The string wsl!12 does not consist of all digits.

Example #2 A ctype_digit() example comparing strings with integers

<?php

$numeric_string = '42';
$integer        = 42;

ctype_digit($numeric_string);  // true
ctype_digit($integer);         // false (ASCII 42 is the * character)

is_numeric($numeric_string);   // true
is_numeric($integer);          // true
?>

注释

Note:

This function expects a string to be useful, so for example passing in an integer may not return the expected result. However, also note that HTML forms will result in numeric strings and not integers. See also the types section of the manual.

Note:

如果给出一个 -128 到 255 之间(含)的整数, 将会被解释为该值对应的ASCII字符 (负值将加上 256 以支持扩展ASCII字符). 其它整数将会被解释为该值对应的十进制字符串.

参见

Ctype 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Check for numeric character(s)

用户评论:

Skippy (25-Oct-2011 09:44)

If you need to check for integers instead of just digits you can supply your own function such as this:

<?php
function ctype_int($text)
{
    return preg_match('/^-?[0-9]+$/', (string)$text) ? true : false;
}
?>

portalpress dot org at gmail dot com (23-May-2011 04:24)

To my surprise after one million iterations:

It took 0.5646638 seconds to false if(('abc'*1 . '')==='abc')
It took 0.5725240 seconds to true if(('123'*1 . '')==='123')
It took 0.3741021 seconds to false if((('abc'*1) . '')==='abc')
It took 0.4357590 seconds to true if((('123'*1) . '')==='123')
It took 0.3529291 seconds to false ctype_digit('abc')
It took 0.3391420 seconds to true ctype_digit('123')

The function ctype_digit() is faster then an inline if().
But this test also shows the value of ((first*1) . second).

mdsky at web dot de (21-May-2010 08:44)

is_numeric gives true by f. ex. 1e3 or 0xf5 too. So it's not the same as ctype_digit, which just gives true when only values from 0 to 9 are entered.

John Saman (05-Feb-2010 01:38)

Using is_numeric function is quite faster than ctype_digit.

is_numeric took 0.237 Seconds for one million runs. while ctype_digit took 0.470 Seconds.

strrev xc tod noxeh ta ellij (14-Dec-2009 04:41)

ctype_digit() will treat all passed integers below 256 as character-codes. It returns true for 48 through 57 (ASCII '0'-'9') and false for the rest.

ctype_digit(5) -> false
ctype_digit(48) -> true
ctype_digit(255) -> false
ctype_digit(256) -> true

(Note: the PHP type must be an int; if you pass strings it works as expected)

walter (09-Dec-2009 10:18)

I was looking at whether this would save time on the numerous input validations I make in legions of scripts.  Typically I use a function numbers_only() which simply does a preg_replace() to remove non-digits from a string.

To test for a possible speedup, I created a new function which only performed the preg_replace() once a type_digit() check had failed.

The results for 1 million interations showed that using ctype_digit() beforehand caused approximately 1/3rd additional latency on strings that were going to be preg_replace()'d anyway (ie: strings that did not contain only digits).  It caused an over 100% speedup over that (latency inclusive) time for input strings that were pure numbers.  The speedup was around 2/3 of the original blind preg_replace().

The lesson for me is that it's only worth trying to optimise away preg_replace() using ctype_digit() or similar if you know with some certainty that the vast majority of your inputs will lean one way or the other.

Having said that, ctype_digit() seems to be cosnistently 30% faster than preg_match().  But adding the additional PHP option as a requirement for your codebase may not justify the optimisation.

Let's face it: PHP aint exactly assembler, even if it is much faster than ruby :)

Chris (02-Aug-2009 08:17)

Remove all non-printable characters from a string:
<?php
$str = implode('', array_filter(str_split($str, 1), 'ctype_print'));
?>

Peter de Pijd (18-Jul-2009 11:53)

Note that an empty string is also false:
ctype_digit("") // false

a_p_leeming at hotmail dot com (25-May-2009 02:17)

Also note that

<?php ctype_digit("-1");   //false ?>

raul dot 3k at gmail dot com (09-Apr-2009 04:21)

The ctype_digit can be used in a simple form to validate a field:
<?php
$field = $_POST["field"];
if(!ctype_digit($field)){
  echo "It's not a digit";
}
?>

Note:
Digits is 0-9

Anonymous (19-Nov-2008 09:56)

Indeed, ctype_digit only functions correctly on strings. Cast your vars to string before you test them. Also, be wary and only use ctype_digit if you're sure your var contains either a string or int, as boolean true for ex will convert to int 1.

To be truly safe, you need to check the type of the var first. Here's a wrapper function that improves upon ctype_digit's broken implementation:

<?php

// replacement for ctype_digit, to properly
// handle (via return value false) nulls,
// booleans, objects, resources, etc.
function ctype_digit2 ($str) {
    return (is_string($str) || is_int($str) || is_float($str)) &&
        ctype_digit((string)$str);
}

?>

If, like me, you're not willing to take a chance on ctype_digit having other problems, use this version:

<?php

// replacement for ctype_digit, to properly
// handle (via return value false) nulls,
// booleans, objects, resources, etc.
function ctype_digit2 ($str) {
    return (is_string($str) || is_int($str) || is_float($str)) &&
        preg_match('/^\d+\z/', $str);
}

?>

minterior at gmail dot com (10-Sep-2007 03:43)

I use ctype_digit() function as a part of this IMEI validation function.

<?php

/**
 * Check the IMEI of a mobile phone
 * @param $imei IMEI to validate
 */
function is_IMEI_valid($imei){   
    if(!ctype_digit($imei)) return false;
    $len = strlen($imei);
    if($len != 15) return false;

    for($ii=1, $sum=0 ; $ii < $len ; $ii++){
        if($ii % 2 == 0) $prod = 2;
        else $prod = 1;
        $num = $prod * $imei[$ii-1];
        if($num > 9){
          $numstr = strval($num);
          $sum += $numstr[0] + $numstr[1];
        }else $sum += $num;
    }

    $sumlast = intval(10*(($sum/10)-floor($sum/10))); //The last digit of $sum
    $dif = (10-$sumlast);
    $diflast = intval(10*(($dif/10)-floor($dif/10))); //The last digit of $dif
    $CD = intval($imei[$len-1]); //check digit

    if($diflast == $CD) return true;

    return false;
}
?>