ctype_digit

(PHP 4 >= 4.0.4, PHP 5)

ctype_digitControlla i caratteri numerici

Descrizione

bool ctype_digit ( string $text )

Controlla che tutti i caratteri nella string, text, fornita siano numerici.

Elenco dei parametri

text

La stringa da testare.

Valori restituiti

Restituisce TRUE se ogni carattere nella stringa text è una cifra decimale, FALSE in caso contrario.

Log delle modifiche

Versione Descrizione
5.1.0 Prima di PHP 5.1.0, questa stringa restituiva TRUE quando text era una stringa vuota.

Esempi

Example #1 Un esempio di ctype_digit()

<?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";
    }
}
?>

Il precedente esempio visualizzerà:

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 Un esempio di ctype_digit() confrontando stringhe con interi

<?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
?>

Note

Nota:

Questa funzione si aspetta una string per essere utile, quindi per esempio passare un integer potrebbe non restituire il risultato aspettato. Comunque, è da notare anche che i form HTML verranno tradotti in stringhe numeriche e non in interi. Vedere anche la sezione tipi del manuale.

Nota:

Se è fornito un integer tra -128 e 255, viene interpretato come il valore ASCII di un singolo carattere (ai valori negativi viene aggiunto 256 in modo da permettere i caratteri Extended ASCII). Qualsiasi altro intero è interpretato come una stringa contenente le cifre decimali dell'intero.

Vedere anche:

  • ctype_alnum() - Controlla i caratteri alfanumerici
  • ctype_xdigit() - Controlla i caratteri che rappresentano una cifra esadecimale
  • is_numeric() - Verifica se una variabile è un numero o una stringa numerica
  • is_int() - Verifica se una variabile è di tipo integer
  • is_string() - Verifica se il tipo di una variabile sia stringa

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User Contributed Notes 10 notes

up
16
info at directwebsolutions dot nl
2 years ago
All basic PHP functions which i tried returned unexpected results. I would just like to check whether some variable only contains numbers. For example: when i spread my script to the public i cannot require users to only use numbers as string or as integer. For those situation i wrote my own function which handles all inconveniences of other functions and which is not depending on regular expressions. Some people strongly believe that regular functions slow down your script.

The reason to write this function:
1. is_numeric() accepts values like: +0123.45e6 (but you would expect it would not)
2. is_int() does not accept HTML form fields (like: 123) because they are treated as strings (like: "123").
3. ctype_digit() excepts all numbers to be strings (like: "123") and does not validate real integers (like: 123).
4. Probably some functions would parse a boolean (like: true or false) as 0 or 1 and validate it in that manner.

My function only accepts numbers regardless whether they are in string or in integer format.
<?php
   
/**
     * Check input for existing only of digits (numbers)
     * @author Tim Boormans <info@directwebsolutions.nl>
     * @param $digit
     * @return bool
     */
   
function is_digit($digit) {
        if(
is_int($digit)) {
            return
true;
        } elseif(
is_string($digit)) {
            return
ctype_digit($digit);
        } else {
           
// booleans, floats and others
           
return false;
        }
    }
?>
up
7
rlerne at gmail dot com
1 year ago
Interesting to note that you must pass a STRING to this function, other values won't be typecasted (I figured it would even though above explicitly says string $text).

I.E.

<?PHP
$val
= 42; //Answer to life
$x = ctype_digit($val);
?>

Will return false, even though, when typecasted to string, it would be true.

<?PHP
$val
= '42';
$x = ctype_digit($val);
?>

Returns True.

Could do this too:

<?PHP
$val
= 42;
$x = ctype_digit((string) $val);
?>

Which will also return true, as it should.
up
6
John Saman
4 years ago
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.
up
6
strrev xc tod noxeh ta ellij
4 years ago
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)
up
7
a_p_leeming at hotmail dot com
5 years ago
Also note that

<?php ctype_digit("-1");   //false ?>
up
6
Peter de Pijd
5 years ago
Note that an empty string is also false:
ctype_digit("") // false
up
1
raul dot 3k at gmail dot com
5 years ago
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
up
0
Skippy
3 years ago
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;
}
?>
up
0
mdsky at web dot de
4 years ago
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.
up
-12
Anonymous
6 years ago
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);
}

?>
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