hello friends
I've started programming in c recently . following are the details about scene:


* vim is editor and program is compiled in gcc
* whenever a program involving math function appears it gives error i.e
though math.h is included in header file compiler complains about it
it gives error of unrecognized function that math function like sqrt, etc
* question is how to connect math.h to a program.

-lm
... and reading some documentations...

1 members found this post helpful.

Enter

C math library

into favorite WEB search engine and read the matches.

When you compile your program with gcc you will also (typically) invoke the linker as well. For an overview: the compiler converts your source code to object code (it takes something that you can read into something that the computer can read) the compiler does this for each source code file generating one object fiel for each source code file that you have in your program; the linker joins all of this object code together (along with any libraries you are using) to form an executable.

The Maths library alos need to be linked in but it doesn't get linked in by default. So you will need to tell it to link in the maths library, that is where the switch -lm comes into play.

If you have one source code file called myCalc.c, which uses the maths library, and you want your program to be called calc, use the following command:

1 members found this post helpful.

Which I did. Ten matches came up:
Two for C++
One for Python
Two for vendor version of Maths libraries

Of the remaining five matches only one mentioned linking but for someone who doesn't understand the linking process its significance would be very easy to miss.

Incidentally, the clearest advice came from a C++ specific page.
cppreference.com

In summary you advice would have been of very little help to someone who was just stating to learn to program and hadn't yet understood the nuances of gcc.

So please, don't just tell people to use a search engine as if it is a panacea, context is important and often that is what people lack when they come to LinuxQuestions.

You know what, one more word needs to be added:

C math library linking

- try in Yahoo. Fifth match in my case.

Such questions (requiring only keywords search) are ridiculous and are kinder garden level.

The very first sign of alarm is the "connect" word the OP used. It looks like the OP's problems are much deeper than the math library.

And

C math library tutorial

yields useful links.

At one point in time we were all in kindergarten and so such questions are not ridiculous. Just part of the learning process.

Here is hard evidence (just "c math library") - see the attachment, bottom of the picture - the answer is in the picture:

I see it as a case of utter laziness.

Attached Thumbnails

 

Yes it is. If you do exactly the right search and know exactly where to look. And the OP is posting here because they do not know those things.


I agree with graemef. Please stop perpetually chastising people just because they don't know as much as you. That's why they're here.

Nowadays people know how to use WEB search engines from the(ir) teen age.

The legitimate questions to ask are the ones which can't be easily answered through keyword search.

For example, suppose one has a map of a city with SRC and DST points on it and asks about an algorithm regarding finding the shortest way between the two points. In order to find the algorithm(s) one has to know the "traveling salesman problem" term, which is not obvious. For example, I learned about the term in English less than 10 years ago, though I knew the term in a different language.

In the OP's case plain keyword search yields an answer even without visiting the URLs returned by the search engines (see the attachment in an earlier post of mine).

Going off topic for a moment this assumption is completely incorrect. The global internet penetration is about 26% for more details see Internet World Stats.

As you pointed out earlier the original poster was unaware of the term linking and so by you very definition the question was valid and so didn't warrant you condescending approach.

This arguement about how to use searching is not helping the OP, so let's stop now---OK?

Sergei;
You are of course correct about finding things on Google, but less experienced people often do not know how to do this efficiently. I suggest a less confrontational approach.

Then he shouldn't be doing "C" programming in the first place (with any library). I.e. the whole thread is invalid - it's like "how do I build a rocket not even bothering to learn physics ?".

To be more particular, the first match Yahoo yields on "gcc tutorial" is http://pages.cs.wisc.edu/~beechung/ref/gcc-intro.html .

In the tutorial:

.

Entering into Yahoo "GNU gcc library" as the 5-th match yields http://www.network-theory.co.uk/docs...cintro_79.html , in it :

.

I.e. two very basic keyword searches yield the needed knowledge (both the particular knowledge regarding the math library and the "link" term) if one makes at least the minimal decency effort. I remember I heard at work from a colleague "It takes so much times to read manuals, that's why I'm asking you". And this is really bothering. I.e. the guy didn't want to read the manual even after being told which one to read.

The answer to all such threads should be: "Have you been banned on all WEB search engines ?".

1 members found this post helpful.

And there are some people that should not even get out of bed in the morning, n'est-ce pas?

I understand your frustration with people who seem to be too lazy to search for things, but please consider toning it down a bit.

shridhar005;
If you still need help, please start a new thread. Be sure to tell us what Google searches you have done.