Shrink Files in C?

[Jumpertka]

Does anyone know, how I can shrink a file in C.
Without copying into a buffer an recopying or something like that. Only open the file, make a cut on a position.
Is there a way in C?

 

[ArkM]

It's not a C topic: it's OS function. For example, MS Windows can't truncate files in so manner, but IBM MVS can do it.
Accordingly no such function(s) in C Standard library.
Portable code must do this op vith rewriting a new file then renaming.
Luckily for us, it's the most safe method too...

 

[marsd]

POSIX specifies truncate and ftruncate for this operation.
man 2 ftruncate.