Php if defined
- Php if defined variable
- Php if defined constant
- Php if defined function
- Php check if defined
- Php if not defined
- Php check if defined constant exists
- Php if not defined constant
- Php if not defined function
- Php define if not defined
- 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