ubuntu 中How to fix undefined reference to `sqrt' in Eclipse

Friday, September 23, 2011

How to fix undefined reference to `sqrt' in Eclipse

Re: How to use math.h in Eclipse with gcc? [message #214058 is a reply to message #213974] Wed, 16 April 2008 04:50   Tracy Miranda Messages: 15 Registered: July 2009 Junior Member   Hi Warren, The "-lm" option is a linker option - looks like you've added it to the  Compiler 'Other flags', where it has no effect. Add it to the linker options, Libraries-> add it in as a new library "m",  this will automatically add on the -l to the option. (Alternately, you can add "-lm" to the Miscellaneous->Linker Flags box, but  I highly recommend the previous option). Tracy "Warren Tang" <warren.c.tang@gmail.com> wrote in message  news:fu2ftr$bai$1@build.eclipse.org... > > I tried to add the "-lm" option for gcc in the project properties: > -c -fmessage-length=0 -std=c99 -lm > > However the eclipse still complains that: > undefined reference to `sqrt' >

Math.h problem 
Programming in C using Eclipse in Linux is great, however when i added variables that were doubles into the "sqrt" function from the "math.h" library there was a problem that came up.

undefined reference to `sqrt'

After a little bit of research, in Eclipse, go to Project > Properties > C/C++ Build > Settings > GCC C Linker > Miscellaneous > add "-lm" to the "Linker Flags" text field. That way it is properly linked to the project.

http://cboard.cprogramming.com/c-programming/88943-undefined-reference-sqrt.html