id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
6812	"boost::lexical_cast<float>(""."") returns 0 instead of throwing"	Bruce Merry <bmerry@…>	Antony Polukhin	"The attached program reports
{{{
boost::lexical_cast<float>(""."") returns 0
}}}
when it should report an exception. According to the lexical_cast docs, lexical_cast<float>(string) is supposed to be equivalent to
 - using stream extraction, which in turn is defined in terms of
 - num_get on the numeric facet, which is defined in terms of
 - strtold in the C standard, which requires
 - ""a non-empty sequence of decimal digits, optionally containing a decimal-point character""
strtold also refers to the grammar for a floating-point literal, which is pretty clear that either the part before or the part after the decimal point has to be non-empty.
 
Compiler is MSVC 2010 SP1. I haven't messed around with locales at all so it's whatever the default is for an English install of Windows 7.

This works with Boost 1.46 under GCC 4.6 - I'm guessing because 1.46 left parsing of float strings to operator>>."	Bugs	closed	Boost 1.50.0	lexical_cast	Boost 1.48.0	Regression	fixed