[ILUG] Very basic C question

[Niall Brady]

On Thu, 30 May 2002 16:52:56 BST, =?iso-8859-1?B?TeFpcnTtbiBPIFN1bGxpdmFu?= said:
>This is probably very simple but I've just started to learn to program C on
>an old Linux box (distribution is SuSE from about four years ago). Problem
>is gcc (which I'm assuming is the right compiler) doesn't seem to be
>recognising any of the .h files. I've included them in the code correctly
>but any functions relating to them are going unrecognised by the compiler
>and it spits out an error.
>The problem in question is math.h and the fmod function.
>
>Is there a path which must be set for gcc?
>
>I'm guessing this is incredibly simple but it's been a long time since I've
>been using linux so hopefully you lot should be able to sort is out.

If the error you're getting looks something like

	/tmp/ccgP0Yjc.o: In function `main':
	/tmp/ccgP0Yjc.o(.text+0x1c): undefined reference to `cos'

it may just be that you need to link off the maths libraries... try
doing this for your compile instead...

	gcc -o test test.c -lm
			   ^^^

That bit is what tells the compiler what libraries it needs to look
for... libm is the maths library.

[If you do (for example)

	man cos
	
 you'll see a section up the top which says LIBRARY.  That has the
 line down the end (-lm) which you'll need to give to the compiler.
 Same counts for other stuff...]

-- 
	Niall