Best search algorithm to find condition within a range

Marko Rauhamaa marko at pacujo.net
Thu Apr 9 15:33:39 CEST 2015


Dave Angel <davea at davea.name>:

> So the C standard can specify such things as undefined. The
> architecture still will do something specific, right or wrong, and
> that's what Marko's claim was about. The C compiler has separate types
> for unsigned and for signed, while the underlying architecture of
> every twos complement machine I have used did add, subtract, and
> multiply as though the numbers were unsigned (what you call modular
> arithmetic).

Alain did have a point. *If* I had used int64_t in my algorithm, it
might not have worked because the compiler could legally produce code
that crashes or does weird things in case of a signed integer overflow.

In this day and age, heavily optimized compilers (including gcc)
actively exploit undefined behavior in code generation.

However, I didn't use int64_t, I used uint64_t.


Marko



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