On 01/26/2012 04:57 PM, Avinash Sonawane wrote:
Sir,
I am using gcc 4.6.1.
I have few questions regarding -lm switch. Please kindly guide me for the same.
1) Why I need to use -lm flag for math.h even if I had declared the
#include<math.h> in the code?
2) If it's all about linking the library then why I don't have to do
the same thing with stdio.h too?
3) Or we have to add the -l'library' switch for every library excluding stdio.h?
4) In case if the -l'library' switch is used for some specific
libraries only then please direct me to the complete list of such
libraries.
Thanks.
--
Avinash Sonawane
PICT Pune
India
1. This depends on which gcc language you use. Requirement to set -lm
explicitly is traditional "legacy" for C, but not for e.g. fortran,
C++,.... It's unusual for a compiler to keep a list of headers you
include and figure out the corresponding libraries required at link time.
2. <stdio.h> library support is always searched in C programs,
regardless of your use of the header.
4. As gcc itself doesn't supply many of the standard C library
functions, you must use the facilities of your implementation (possibly
linux, possibly something entirely different) to see which libraries are
available. gcc -v may show you which libraries are searched.
--
Tim Prince
