Variable Functions

empty --> Tests whether the variable specified is empty.
Format: $bool = empty($varname);
get_defined_classes
Creates an array containing the names of all the classes in the script, including those in included files.
Format: $array_classes = get_defined_classes();
get_defined_constants --> Creates an associative array of all the constants.
Format: $array_constants = get_defined_constants();
get_defined_functions --> Creates an array with names of all functions.
Format: $array_functions = get_defined_functions();
get_defined_vars --> Creates an array of all variables.
Format: $array_vars = get_defined_vars();
isset --> Checks whether variable is set.
Format: $bool = isset($varname);
print_r --> Outputs contents of a variable.
Format: print_r($varname);
putenv --> Sets an environmental variable as specified by setting. setting is usually name=value.
Format: putenv(“setting”);
serialize
Converts data into a string containing binary data. Used to store data in a file or database. The specified variable can be any type, including an object or a function.
Format: $string_ser = serialize($variable);
unserialize --> Converts serialized data back to its original form.
Format: $variable = unserialize($string_ser);
unset --> Removes a variable.
Format: unset($varname);
var_dump --> Outputs contents of a variable.
Format: var_dump($varname);