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    intval

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

    intval — Estrae il valore intero da una variabile

    Descrizione

    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

    var

    Valore scalare da convertire in intero

    base

    Base per la conversione

    Nota:

    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 .

    Esempi

    Example #1 Esempi di uso di intval()

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

    <?php
    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
    ?>

    Note

    Nota:

    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

    up
    336
    Ken
    13 years ago
    Not mentioned elsewhere: intval(NULL) also returns 0.
    up
    143
    winbill at hotmail dot com
    14 years ago
    Be careful :

    <?php
    $n    ="19.99";
    print     intval($n*100); // prints 1998
    print intval(strval($n*100)); // prints 1999
    ?>
    up
    69
    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.

    <?php
    echo intval('1e5');
    ?>

    will return 1 on PHP 5.6 and PHP 7.0,
    but it will return 100000 on PHP 7.1.
    up
    50
    zak at php dot net
    24 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 (http://www.php.net/manual/language.types.double.php)

    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
    up
    35
    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:
    1999
    1999
    1999

    actual output
    1999
    1998
    1999

    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.
    up
    38
    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():

    <?php
    echo intval("0x1a", 0), "\n"; // hex; prints "26"
    echo intval("057", 0), "\n"; // octal; prints "47"
    echo intval("42", 0), "\n"; // decimal; prints "42"
    ?>
    up
    5
    Anonymous
    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
    up
    7
    Anthony
    6 years ago
    The binary notation is NOT supported until php7.2
    <?php
                                 // 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
    ?>
    up
    13
    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:

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

    echo     int('j18ugj9hu0gj5hg');
    //output: 18
    ?>
    this example returns an int, so it will follow the int rules, and has support for negative values.

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

    echo     int('j-1809809808908099878758765ugj9hu0gj5hg');
    //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.
    up
    5
    Anony Moose
    4 years ago
    As a warning, do not use this function alone for input validation.

    Vulnerable example:
    <?php
    if(isset($_GET['id']) && intval($_GET['id']) > 0){
        echo     $id;
    }
    ?>

    The following requests would pass this filter:

    /page.php?id=10
    /page.php?id=10oops
    /page.php?id=10<script>alert(1)</script>
    /page.php?id=1' OR '1'='1
    /page.php?id[]=<script>alert(1)</script>

    Instead use the is_numeric() function for integer validation:

    <?php
    echo intval("10oops"); // 10
    echo is_numeric("10oops");  // false
    ?>

    Secure example:
    <?php
    if(isset($_GET['id']) && is_numeric($_GET['id']) && intval($_GET['id']) > 0){
        echo     $id;
    }
    ?>
    up
    7
    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. :)
    up
    5
    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).
    up
    6
    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 />";

    819.99999999999988631316
    819
    819
    820
    up
    1
    taylorsarrafian at gmail dot com
    9 years ago
    beware:

    <?php

           // 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 ) {
          return     intval( strval( $n * 100 ) / 100 );
       }

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

    ?>
    up
    2
    yves
    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
    <?php
      intval    ('42', 8); // => 34
          intval(42, 8);   // => 42 !
    ?>
    PHP considers the 42 as being already an integer, and doesn't apply any conversion. And supplying
    <?php
      intval    (49, 8);  // => 49 !
    ?>
    produces no error and no warning.
    up
    1
    Denes Kellner
    10 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("123.ee-2") - 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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