C++ most efficient way to convert string to int (faster than atoi)

Question

As mentioned in the title, I\'m looking for something that can give me more performance than atoi. Presently, the fastest way I know is

atoi(mystring.c_str(         


        

Answer 1

atoi can be improved upon significantly, given certain assumptions. This was demonstrated powerfully in a presentation by Andrei Alexandrescu at the C++ and Beyond 2012 conference. Hi s replacement used loop unrolling and ALU parallelism to achieve orders of magnitude in perf improvement. I don't have his materials, but this link uses a similar technique: http://tombarta.wordpress.com/2008/04/23/specializing-atoi/