2.5. Alternatives to Wrapper #ifndef
2.5 Alternatives to Wrapper #ifndef
CPP supports two more ways of indicating that a header file should be read only once. Neither one is as portable as a wrapper ‘#ifndef
’ and we recommend you do not use them in new programs, with the caveat that ‘#import
’ is standard practice in Objective-C.
CPP supports a variant of ‘#include
’ called ‘#import
’ which includes a file, but does so at most once. If you use ‘#import
’ instead of ‘#include
’, then you don't need the conditionals inside the header file to prevent multiple inclusion of the contents. ‘#import
’ is standard in Objective-C, but is considered a deprecated extension in C and C++.
‘#import
’ is not a well designed feature. It requires the users of a header file to know that it should only be included once. It is much better for the header file's imp