I'm parsing GPS status entries in fixed NMEA sentences, where fraction part of geographical minutes comes always after period. However, on systems where locale defines comma as decimal separator, atof function ignores period and whole fraction part.
What is the best method to deal with this issue? Long/latitude string in stored in character array, if it matters.
Example Code:
m_longitude = atof((char *)pField);
Where
pField[] = "01000.3897";
Cross-platform project, compiled for Windows XP and CE.
Comment to solution:
Accepted answer is more elegant, but this answer (and comment) is also worth knowing as a quick fix
Answer
You could always use (modulo error-checking):
#include <sstream>
...
float longitude = 0.0f;
std::istringstream istr(pField);
istr >> longitude;
The standard iostreams use the global locale by default (which in turn should be initialized to the classic (US) locale). Thus the above should work in general unless someone previously has changed the global locale to something else, even if you're running on a non-english platform. To be absolutely sure that the desired locale is used, create a specific locale and "imbue" the stream with that locale before reading from it:
#include <sstream>
#include <locale>
...
float longitude = 0.0f;
std::istringstream istr(pField);
istr.imbue(std::locale("C"));
istr >> longitude;
As a side note, I've usually used regular expressions to validate NMEA fields, extract the different parts of the field as captures, and then convert the different parts using the above method. The portion before the decimal point in an NMEA longitude field actually is formatted as "DDDMM.mmm.." where DDD correspond to degrees, MM.mmm to minutes (but I guess you already knew that).