#ifndef
Preprocessor conditional directive
Syntax
`
#ifndef symbol
' Conditionally included statements
#endif
`
Description
Conditionally includes statements at compile time.
Statements within the `#ifndef...#endif` block are included if `symbol` is not defined and excluded (ignored) if symbol is defined.
`#ifndef symbol` is equivalent to `#if Not defined(symbol)`
Example
`
#ifndef __MYFILE_BI__
#define __MYFILE_BI__
' Declarations
#endif
`
Differences from QB

- New to FreeBASIC

See also

- `#define`
- `#macro`
- `#if`
- `#else`
- `#elseif`
- `#endif`
- `#ifdef`
- `#undef`
- `defined`