Php variables

- Php variables in string
- Php variables to array
- Php variables_order
- Php variables types
- Php variables inside string
- Php variables scope
- Php variables in js
- Php variables in interface
- Php variables in echo
- Php variables in html
- Php variables camelcase or underscore
- Php variables declaration
- Php variables variable
- Php variables list
- Php variables without dollar sign