Not to belabour the point, but try the internal documentation / google.
For example perldoc -f sprintf would have helped you with this question. The -f means that you are looking up an internal function.

C:\>perldoc -?
Unknown option: ?
perldoc [options] PageName|ModuleName|ProgramName...
perldoc [options] -f BuiltinFunction
perldoc [options] -q FAQRegex
[download]

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Zak
Pluralitas non est ponenda sine neccesitate - mysql's philosphy