http://kor.i2p/books/The%20C%20Programming%20Language%20by%20K&R/chapter7.html
As a minimum, it should print non-graphic characters
in octal or hexadecimal according to local custom, and break long text lines. 7.3 Variable-length Argument Lists This section contains an implementation of a minimal version of printf , to show how to write a function that processes a
variable-length argument list in a portable way.