is_resource
Here's a little function that will test whether a variable can be used as offset to an array.
<?php
function is_offset(&$var) {
return (is_scalar($var) || is_null($var)) && !is_resource($var);
}
?>
The resource check is currently redundant, but according to the manual that may change in the future.
is_scalar
(PHP 4 >= 4.0.5, PHP 5)
is_scalar — Informa se é uma váriavel escalar
Descrição
Verifica se a dada variável é uma escalar.
Variáveis escalares são as que contém integer, float, string ou boolean. os tipos array, object e resource não são escalares.
Nota:
is_scalar() não considera o tipo resource como um valor escalar, apesar de tipos resouce ser uma abstração de dados, atualmente baseados em inteiros. Esse detalhe de implementação poderá ser modificado futuramente.
Parâmetros
- var
-
A variável a ser avaliada.
Valor Retornado
Retorna TRUE se var é um escalar, FALSE caso contrário.
Exemplos
Exemplo #1 Exemplo da is_scalar()
<?php
function show_var($var)
{
if (is_scalar($var)) {
echo $var;
} else {
var_dump($var);
}
}
$pi = 3.1416;
$proteins = array("hemoglobin", "cytochrome c oxidase", "ferredoxin");
show_var($pi);
show_var($proteins)
?>
O exemplo acima irá imprimir:
3.1416
array(3) {
[0]=>
string(10) "hemoglobin"
[1]=>
string(20) "cytochrome c oxidase"
[2]=>
string(10) "ferredoxin"
}
Veja Também
- is_float() - Informa se a variável é do tipo float
- is_int() - Informa se a variável é do tipo inteiro
- is_numeric() - Informa se a variável é um número ou uma string numérica
- is_real() - Sinônimo de is_float
- is_string() - Informa se a variável é do tipo string
- is_bool() - Verifica se a variável é um boleano
- is_object() - Informa se a variável é um objeto
- is_array() - Verifica se a variável é um array
User Contributed Notes
is_scalar
is_scalar
webmaster at oehoeboeroe dot nl
04-May-2009 09:15
04-May-2009 09:15
31-Jul-2006 05:59
Another warning in response to the previous note:
> just a warning as it appears that an empty value is not a scalar.
That statement is wrong--or, at least, has been fixed with a later revision than the one tested. The following code generated the following output on PHP 4.3.9.
CODE:
<?php
echo('is_scalar() test:'.EOL);
echo("NULL: " . print_R(is_scalar(NULL), true) . EOL);
echo("false: " . print_R(is_scalar(false), true) . EOL);
echo("(empty): " . print_R(is_scalar(''), true) . EOL);
echo("0: " . print_R(is_scalar(0), true) . EOL);
echo("'0': " . print_R(is_scalar('0'), true) . EOL);
?>
OUTPUT:
is_scalar() test:
NULL:
false: 1
(empty): 1
0: 1
'0': 1
THUS:
* NULL is NOT a scalar
* false, (empty string), 0, and "0" ARE scalars
docey
20-May-2006 04:02
20-May-2006 04:02
just a warning as it appears that an empty value is not a scalar.
although the manual says scalars are:
-> integers (eg. 243)
-> floats (eg. 14.4)
-> strings (eg "this is a string")
-> booleans (eg true or false)
this might seem easy but rembere that empty values are:
-> NULL
-> false
-> empty string
-> 0
-> "0"
thus the true list of scalars must be:
-> integers large then zero
-> floats larger then zero
-> strings with a lenght large then zero
-> string that do not contain only the number 0
-> boolean value of true.
especialy the boolean value false can be tricky as true is
considerd to be scalar but false is not. or a string that is
initialized with a zero lenght here's an example.
$string = ""; //initialize our string.
function store_var($var)
{
if(is_scalar($var)){
print("our var is a scalar.");
}else{
print("you tried to store something else here.");
}
}
$this->store_var($string); // does not work as expected
this might be usefull when you create method to store a
variable inside a class but do not want to store other stuff
like object, arrays or resources, but storing an empy value
is oke. then is_scalar does not work as empty values are
incorrectly not seens as a bool, string, integer or float.
this is an important downside to is_scalar wich might cause
some people to loose there hair from headscrachting.
this might be added to the manual as a warning or something.
efelch at gmail dot com
17-Aug-2005 11:31
17-Aug-2005 11:31
A scalar is a single item or value, compared to things like arrays and objects which have multiple values. This tends to be the standard definition of the word in terms of programming. An integer, character, etc are scalars. Strings are probably considered scalars since they only hold "one" value (the value represented by the characters represented) and nothing else.
Dr K
14-Aug-2005 12:48
14-Aug-2005 12:48
Having hunted around the manual, I've not found a clear statement of what makes a type "scalar" (e.g. if some future version of the language introduces a new kind of type, what criterion will decide if it's "scalar"? - that goes beyond just listing what's scalar in the current version.)
In other lanuages, it means "has ordering operators" - i.e. "less than" and friends.
It (-:currently:-) appears to have the same meaning in PHP.
popanowel HAT hotmailZ DOT cum
14-May-2004 09:31
14-May-2004 09:31
Hi ... for newbees here, I just want to mention that reference and scalar variable aren't the same. A reference is a pointer to a scalar, just like in C or C++.
<? php // simple reference to scalar
$a = 2;
$ref = & $a;
echo "$a <br> $ref";
?>
this should print out: "2 <br> 2".
Scalar class also exists. Look below:
<? php
class Object_t {
var $a;
function Object_t () // constructor
{
$this->a = 1;
}
}
$a = new Object_t; // we define a scalar object
$ref_a = &a;
echo "$a->a <br> $ref->a";
?>
again, this should echo: "1 <br> 1";
Here is another method isued in OOP to acheive on working only over reference to scalar object. Using this, you won't ever have to ask yourself if you work on a copy of the scalar or its reference. You will only possess reference to the scalar object. If you want to duplicate the scalar object, you will have to create a function for that purpose that would read by the reference the values and assign them to another scalar of the same type... or an other type, it is as you wish at that moment.
<?php
class objet_t {
var $a;
function object_t
{
$this->a = "patate_poil";
}
}
function &get_ref($object_type)
{
// here we create a scalar object in memory
// and we return it by reference to the calling
// control scope.
return &new $object_type;
}
$ref_object_t = get_ref(object_t);
echo "$ref_object_t->a <br>";
?>
this should echo: "patate_poit <br>".
The only thing that I try to demonstrate is that scalar variable ARE object in memory while a reference is usualy a variable (scalar object) that contain the address of another scalar object, which contain the informations you want by using the reference.
Good Luck!
otek is popanowel HAT hotmailZ DOT cum
bps7j at yahoNOSPAMo.com
08-Feb-2004 07:56
08-Feb-2004 07:56
is_scalar(null) is false. Apparently a variable needs to have a value to be considered a scalar.