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Last updated: Thu, 19 May 2005

is_scalar

(PHP 4 >= 4.0.5, PHP 5)

is_scalar --  Finds whether a variable is a scalar

Description

bool is_scalar ( mixed var )

Finds whether the given variable is a scalar.

Scalar variables are those containing an integer, float, string or boolean. Types array, object and resource are not scalar.

Note: is_scalar() does not consider resource type values to be scalar as resources are abstract datatypes which are currently based on integers. This implementation detail should not be relied upon, as it may change.

Parameters

var

The variable being evaluated.

Return Values

Returns TRUE if var is a scalar FALSE otherwise.

Examples

Example 1. is_scalar() example

<?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)

?>

The above example will output:

3.1416
array(3) {
  [0]=>
  string(10) "hemoglobin"
  [1]=>
  string(20) "cytochrome c oxidase"
  [2]=>
  string(10) "ferredoxin"
}



User Contributed Notes
is_scalar
popanowel HAT hotmailZ DOT cum
14-May-2004 02:31
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 11:56
is_scalar(null) is false.  Apparently a variable needs to have a value to be considered a scalar.

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 Last updated: Thu, 19 May 2005
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Last updated: Thu May 19 17:35:34 2005 CDT