Php check if defined
- Php check if defined constant exists
- Php check if defined variable exists
- Php check if variable defined
- Php check if function defined
- Php check if class defined
- Php check if property defined
- Php check if var defined
- Php check if not defined
- Php check if constant is defined in class
- Php check if array key defined
- Php check if constant already defined
- Php check if method is defined
- Php check if object is defined
- Php check if variable is not defined
- Php check if global constant is defined