PHP provides many standard functions available, the following table lists some of the commonly used ones:
| function | describe |
|---|
| boolval | Get the boolean value of a variable |
| debug_zval_dump | Check the reference count and type information of a variable in the zend engine |
| doubleval | alias for floatval |
| empty | Check if a variable is empty |
| floatval | Get the floating point value of a variable |
| get_defined_vars | Returns an array consisting of all defined variables |
| get_resource_type | Return resource type |
| gettype | Get the type of variable |
| import_request_variables | Import GET/POST/Cookie variables into the global scope |
| intval | Get the integer value of a variable |
| is_array | Check if a variable is an array |
| is_bool | Check if a variable is of type Boolean |
| is_callable | Check whether the parameter is a legal callable structure |
| is_double | Alias for is_float |
| is_float | Check whether the variable is of floating point type |
| is_int | Check if a variable is an integer |
| is_integer | Alias for is_int |
| is_iterable | Check whether the content of a variable is an iterable value |
| is_long | Alias for is_int |
| is_null | Check if a variable is NULL |
| is_numeric | Check if a variable is a number or a string of numbers |
| is_object | Check if a variable is an object |
| is_real | Alias for is_float |
| is_resource | Check whether the variable is a resource type |
| is_scalar | Check if a variable is a scalar |
| is_string | Check if a variable is a string |
| isset | Check if a variable is set and non-NULL |
| print_r | Print variables to output easy-to-read information. |
| serialize | serialized object |
| settype | Set the type of variable |
| strval | Get the string value of a variable |
| unserialize | Create a PHP value from a stored representation |
| unset | Release the given variable |
| var_dump | Print information about variables |
| var_export | Output or return a variable, represented as a string |
Password hashing algorithm
| function | describe |
|---|
| password_get_info | Returns information about the specified hash |
| password_hash | Create a hash of the password |
| password_needs_rehash | Checks whether a hash value matches the specified options |
| password_verify | Verify that the password matches the hash value |
