4.Function Testing on Variable

is_null():

function is_null () return true if Variable Worth null or not assign a value.
For example:

<?php

 $x;<br> 

if (is_null(@$x))

   echo "True Condition";

 else

   echo "False Condition";

?>

Result

True Condition

is_integer():

function is_integer return true if Variable value Integer.
For example:

<?php

 $x = 10;

 if (is_integer($x))

   echo "True Condition";

 else

   echo "False Condition";

?>

Result

True Condition

is_bool():

function is_bool () return true if Variable value as a Boolean.
For example:

<?php

 $x = true;

 if (is_bool($x))

   echo "True Condition";

 else

   echo "False Condition";

?>

Result

True Condition

is_string():

function is_string () return true if Variable value as a String.
For example:

<?php

  $x = "This is string";

  if (is_string($x))

    echo "True Condition";

  else

    echo "False Condition";

?>

Result

True Condition

is_double() or is_float() or is_real():

The above three function have the same role it return true if Variable Data fractions.
For example:

<?php

$x = 10;

if (is_double($x))

   echo "True Condition";

else

   echo "False Condition";

?>

Result

False Condition

is_array():

function is_array () return true if Variable Array.
For example:

<?php

$x = 20;

if (is_array($x))

 echo "True Condition";

else

 echo "False Condition";

?>

Result

False Condition

empty():

function empty() return true if Variable value as "" , '' , false , null ,Not exist or has not assign value.
For example:

<?php

 $x = '';<br> if(empty($x))

   echo "True Condition";

 else

   echo "False Condition";

?>

Result

True Condition

isset():

function isset () return true if Variable $ x occurs. Its not really like null yet exist.
For example:

<?php

 $x = 12;

 if (isset($x))

   echo "True Condition";

 else

   echo "False Condition";

?>

Result

True Condition

unset():

function unset () serves Clear the value contained in the Variable from Memory.
For example:

<?php

  $x = 12;

  unset($x);

  echo @$x; // output : nothing because $x is now null

?>

is_numeric():

function is_numeric () return true if $ x is a number or a String.
For example:

<?php

 $x = “12”;

 if (is_numeric($x))

   echo "True Condition";

 else

   echo "False Condition";

?>

Result

True Condition