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(PHP 4, PHP 5, PHP 7, PHP 8)

intvalEstrae il valore intero da una variabile


intval(mixed $var, int $base = 10): int

Estrae il valore intero di var, utilizzando la base definita a parametro per la conversione (la base vale 10 di default). intval() non dovrebbe essere usata sugli oggetti, poichè facendolo emetterà un errore di livello E_NOTICE e restituirà 1.

Elenco dei parametri


Valore scalare da convertire in intero


Base per la conversione


Se base è 0, la base usata è determinata dal formato di var:

  • se la stringa include un prefisso "0x" (o "0X"), la base è considerata 16 (esadecimale); altrimenti,
  • se la stringa inizia con "0", la base è considerata 8 (ottale); altrimenti,
  • la base è considerata 10 (decimale).

Valori restituiti

Il valore intero di var se riesce, oppure 0 in caso di errore. Gli array vuoti restituiscono 0, gli array non vuoti restituiscono 1.

Il valore massimo dipende dal sistema. Nei sistemi a 32 bit si ha come valore per il caso di intero con segno il range da -2147483648 a 2147483647. Così, ad esempio, su tali sistemi, la riga intval('1000000000000') restituirà 2147483647. Il massimo valore per un intero con segno sui sistemi a 64 bit è 9223372036854775807.

Le stringhe probabilmente restituiranno 0, sebbene il valore restituito dipenda dal primo carattere a sinistra della stringa. Si utilizzano le comuni di integer casting .


Example #1 Esempi di uso di intval()

I seguenti esempi sono basati su un sistema a 32 bit.

echo intval(42); // 42
echo intval(4.2); // 4
echo intval('42'); // 42
echo intval('+42'); // 42
echo intval('-42'); // -42
echo intval(042); // 34
echo intval('042'); // 42
echo intval(1e10); // 1410065408
echo intval('1e10'); // 1
echo intval(0x1A); // 26
echo intval(42000000); // 42000000
echo intval(420000000000000000000); // 0
echo intval('420000000000000000000'); // 2147483647
echo intval(42, 8); // 42
echo intval('42', 8); // 34
echo intval(array()); // 0
echo intval(array('foo', 'bar')); // 1



Il parametro base non ha influenza a meno che il parametro var non sia una stringa.

Log delle modifiche

Versione Descrizione
5.1.0 Genera E_NOTICE e restituisce 1, quando un oggetto è passato a var.

Vedere anche:

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User Contributed Notes 16 notes

12 years ago
Not mentioned elsewhere: intval(NULL) also returns 0.
winbill at hotmail dot com
13 years ago
Be careful :

intval($n*100); // prints 1998
print intval(strval($n*100)); // prints 1999
leon at leonidasjp dot nl
7 years ago
It seems intval is interpreting valid numeric strings differently between PHP 5.6 and 7.0 on one hand, and PHP 7.1 on the other hand.

echo intval('1e5');

will return 1 on PHP 5.6 and PHP 7.0,
but it will return 100000 on PHP 7.1.
zak at php dot net
23 years ago
intval converts doubles to integers by truncating the fractional component of the number.

When dealing with some values, this can give odd results. Consider the following:

print intval ((0.1 + 0.7) * 10);

This will most likely print out 7, instead of the expected value of 8.

For more information, see the section on floating point numbers in the PHP manual (

Also note that if you try to convert a string to an integer, the result is often 0.

However, if the leftmost character of a string looks like a valid numeric value, then PHP will keep reading the string until a character that is not valid in a number is encountered.

For example:

"101 Dalmations" will convert to 101

"$1,000,000" will convert to 0 (the 1st character is not a valid start for a number

"80,000 leagues ..." will convert to 80

"1.4e98 microLenats were generated when..." will convert to 1.4e98

Also note that only decimal base numbers are recognized in strings.

"099" will convert to 99, while "0x99" will convert to 0.

One additional note on the behavior of intval. If you specify the base argument, the var argument should be a string - otherwise the base will not be applied.

For Example:

print intval (77, 8); // Prints 77
print intval ('77', 8); // Prints 63
Ben Laurienti
18 years ago
You guys are going to love this. I found something that I found quite disturbing.

$test1 = intVal(1999);

$amount = 19.99 * 100;
$test2 = intVal($amount);
$test3 = intVal("$amount");

echo $test1 . "<br />\n";
echo $test2 . "<br />\n";
echo $test3 . "<br />\n";

expected output:

actual output

Appears to be a floating point issue, but the number 1999 is the only number that I was able to get to do this. 19.99 is the price of many things, and for our purpose we must pass it as 1999 instead of 19.99.
spoon_reloaded at gmail dot com
15 years ago
Here is a really useful undocumented feature:

You can have it automatically deduce the base of the number from the prefix of the string using the same syntax as integer literals in PHP ("0x" for hexadecimal, "0" for octal, non-"0" for decimal) by passing a base of 0 to intval():

echo intval("0x1a", 0), "\n"; // hex; prints "26"
echo intval("057", 0), "\n"; // octal; prints "47"
echo intval("42", 0), "\n"; // decimal; prints "42"
4 years ago
PHP 7.2

$test = intval(150.20*100); //15019
$test2 = intval(15020); //15020
$test3 = intval(15020.0); //15020
$test4 = 150.20*100; //15020.0
6 years ago
The binary notation is NOT supported until php7.2
// PHP <7.2 | PHP >=7.2
echo intval(0b11); // 3 | 3
echo intval(-0b11); // -3 | -3
echo intval('0b11'); // 0 | 0
echo intval('-0b11'); // 0 | 0
echo intval('0b11', 0); // 0 | 3
echo intval('-0b11', 0); // 0 | -3
espertalhao04 at hotmail dot com
11 years ago
if you want to take a number from a string, no matter what it may contain, here is a good solution:

function int($s){return(int)preg_replace('/[^\-\d]*(\-?\d*).*/','$1',$s);}

//output: 18
this example returns an int, so it will follow the int rules, and has support for negative values.

function int($s){return($a=preg_replace('/[^\-\d]*(\-?\d*).*/','$1',$s))?$a:'0';}

//output: -1809809808908099878758765

this one returns a string with just the numeric value.
it also supports negative values.

the latter is better when you have a 32 bit system and you want a huge int that is higher than PHP_MAX_INT.
tuxedobob at mac dot com
20 years ago
Sometimes intval just won't cut it. For example if you want to use an unsigned 32-bit int and need all 32 bits. Recently, I wrote a little script that took and integer and converted it to an IP address. After realizing I couldn't just mod the whole thing, since the sign bit throws it off (and compensating for that), we ran into a problem where if it was entered into a form, the value somehow wasn't converted to an integer properly, at least not implicitly. The solution for this, and the way I recommend converting a string to an integer, is:

$num = $num + 0;

and PHP will leave your number alone; it'll just know it's a number. Such is the fun of a loosely-typed language. :)
Anony Moose
4 years ago
As a warning, do not use this function alone for input validation.

Vulnerable example:
if(isset($_GET['id']) && intval($_GET['id']) > 0){

The following requests would pass this filter:

/page.php?id=1' OR '1'='1

Instead use the is_numeric() function for integer validation:

echo intval("10oops"); // 10
echo is_numeric("10oops"); // false

Secure example:
if(isset($_GET['id']) && is_numeric($_GET['id']) && intval($_GET['id']) > 0){
pfreet at gmail dot com
11 years ago
Do not use intval() when you really want round(). This is due to how PHP handles precision.

echo number_format(8.20*100, 20), "<br />";
echo intval(8.20*100), "<br />";
echo floor(8.20*100), "<br />";
echo round(8.20*100), "<br />";

taylorsarrafian at gmail dot com
9 years ago


// observe the following
echo intval( strval( -0.0001 ) ); // 0
echo intval( strval( -0.00001 ) ); // -1

// this is because
echo strval( -0.0001 ); // -.0001
echo strval( -0.00001 ); // -1.0E-5

// thus beware when using
function trunc2_bad( $n ) {
intval( strval( $n * 100 ) / 100 );

// use this instead
function trunc2_good( $n ) {
intval( floatval( strval( $n * 100 ) ) / 100 );

13 years ago
The behaviour of intval() is interesting when supplying a base, and you better check your intval base-based expressions, as it is counter-intuitive.
As the example shows
('42', 8); // => 34
intval(42, 8); // => 42 !
PHP considers the 42 as being already an integer, and doesn't apply any conversion. And supplying
(49, 8); // => 49 !
produces no error and no warning.
mkamerma at science dot uva dot nl
18 years ago
As addendum, the "if ($int > 0)" check in the encode function is redundant. It doesn't do anything bad to keep it in since it will always be true when reaching that point, but it's a meaningless conditional this way. It's a remnant from when I tried to write the function in terms of bitshifts, which could lead to negative ints when shifting if the 32nd bit was set (instead of always padding with 0's when using >> it pads with 1's leading to negative ints).
Denes Kellner
5 months ago
Warning: intval() parses scientific notation, like "12.3e7".

This comes out of the blue when you use intval() to cut the first integer value from a string; at first glance there's nothing wrong with it, if you have "123.jeff" it will give you 123, but in the rare case of parsing something that has a second segment with a hex number, you can easily run into this. (Let's not start the "why would you parse a string like that" argument.)

So if you're not prepared, these results may surprise you:

intval("") - gives you 123
intval("123.e2-e") - gives you 12300
intval("123.a2-e") - gives you 123
intval("123.e-22") - gives you 0
intval("123.e-a2") - gives you 123
intval("123.e-2a") - gives you 1
intval("123.2e2a") - gives you 12320
intval("123.22e2") - gives you 12322
intval("123.22ea") - gives you 123

Again, this is somewhat expected behaviour once you know that scientific notation is interpreted by it. But it looks like a less-than-widely known fact and I only faced this issue after 20+ years of php.
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