Subject: [Boost-users] [conversion] Using Lexical_cast to convert string to float
From: Ryan McConnehey (mccorywork_at_[hidden])
Date: 2009-06-09 22:36:30
In writing some unit tests to convert strings to floats I've come across
a puzzling situation. I was trying to test that a std::bad_cast was
thrown if a number was too large to fit into a float. The error wasn't
thrown but the float was given 1.#INF000. The work around I used was to
cast to a double and then do a numeric_cast on the result. This
provided an exception for values larger than could fit in a float.
Lexical_cast on a double though works as I would have expected. If a
value is too large to fit into a double then a std::bad_cast is called.
float test = boost::lexical_cast<float>("3.4e050");
//test will have the value of 1.#INF000
float test = boost::numeric_cast<float>(
boost::lexical_cast<double>("3.4e50"); //std::bad_cast is thrown
double test = boost::lexical_cast<double>("3.4e350");
//std::bad_cast is thrown
Is the lexical_cast for float behaving correctly?
Ryan
P.S. This code is using boost 1.38.0