PHP Variable type cast & Create empty Object

PHP does not need (or does not support) explicit type definitions in variable definitions; The variable type is determined by the context in which the variable is used.

That is, if you assign a string value to the variable Var,var it becomes a string. If you assign an integer value to Var, it becomes an integer.
The type casts in PHP are very similar to those in C: precede the variables to be converted with the target type enclosed in parentheses.

 <? PHP   $foo  = 10;  echo  "Before conversion: \ $foo =".  $foo ; //  echo  "<br/>" //  output: $foo =10  echo " <br/> ";   $foo  = (boolean )  $foo ; //  cast to Boolean  echo  "After conversion: \ $foo =".  $foo ; //  output: $foo =1 ?>  

The allowable casts are:

(int), (integer)-Converted to integral type
(bool), (Boolean)-converted to Boolean
(float), (double), (real)-converts to floating-point type
(string)-converts to a string
(array)-Convert an array
(object)-Convert to Object

<? PHP    　　$test = (object) []; // PHP creates an empty object    $test->age = ' + ';     $test->sex = ' 1 ';     Print_r ($test// output Stdclass Object ([age] [sex] = 1)?>

<? PHP     $test New StdClass ();         // PHP creates an empty object    $test->age = ' + ';     $test->sex = ' 1 ';     Print_r ($test// output Stdclass Object ([age] [sex] = 1)?>

PHP Variable type cast & Create empty Object