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copied!<p>Most GPS receivers output the position information using the NMEA protocol, you need a NMEA parser written in C, take a look at <a href="http://nmea.sourceforge.net/" rel="nofollow">NMEA Library</a> as an example.</p> <p>The library contains a number of sample applications, probably the simplest to understand/implement is in the <code>nmealib\samples\parse</code> directory.</p> <pre><code>#include <nmea/nmea.h> #include <string.h> int main() { const char *buff[] = { "$GPRMC,173843,A,3349.896,N,11808.521,W,000.0,360.0,230108,013.4,E*69\r\n", "$GPGGA,111609.14,5001.27,N,3613.06,E,3,08,0.0,10.2,M,0.0,M,0.0,0000*70\r\n", "$GPGSV,2,1,08,01,05,005,80,02,05,050,80,03,05,095,80,04,05,140,80*7f\r\n", "$GPGSV,2,2,08,05,05,185,80,06,05,230,80,07,05,275,80,08,05,320,80*71\r\n", "$GPGSA,A,3,01,02,03,04,05,06,07,08,00,00,00,00,0.0,0.0,0.0*3a\r\n", "$GPRMC,111609.14,A,5001.27,N,3613.06,E,11.2,0.0,261206,0.0,E*50\r\n", "$GPVTG,217.5,T,208.8,M,000.00,N,000.01,K*4C\r\n" }; int it; nmeaINFO info; nmeaPARSER parser; nmea_zero_INFO(&info); nmea_parser_init(&parser); for(it = 0; it < 6; ++it) nmea_parse(&parser, buff[it], (int)strlen(buff[it]), &info); nmea_parser_destroy(&parser); return 0; } </code></pre> <p>When implementing with a GPS receiver, instead of passing the fixed strings (in <code>buff</code>) to the parser you just need to pass the received NMEA strings from the receiver to the parser. The data gathered will be available in the <code>info</code> structure.</p> <p>If you wish to develop your own parser, take a look <a href="http://gpsd.berlios.de/NMEA.txt" rel="nofollow">here</a> for a detailed breakdown of the various messages that may be output from a GPS receiver. Most GPS receivers output only RMC, GGA, GSA, GSV, GLL, VTG, and (rarely) ZDA.</p>

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