Pretty sure druckef should be drucked. printf means print (to) file. “File” is valid German, but it is non-standard and “Datei” seems to be the preferred form.

I could also argue that that d should be capitalised, but I’m already overstepping my bounds considering I know very little German.

I wouldn’t want to say which should take precedence between C’s preference for all-lowercase keywords and functions and German’s Rule to capitalise all Nouns.