CODEWITHSUNDEEP
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Math4lyf
Math4lyf

Reputation: 33

Using header files in C

I'm trying to learn the use of header files in C. Now I found few resources in my research but none of them created the desired effect.

First, according to this tutorial, I can write my functions in the header file itself. But I don't want to do that. I want to keep the header file unchanged even if I changed the code given that the interface remains unchanged.

Answer to this question suggests two methods. First I can write the code and header file separately and include them when I compile as follows:

gcc -o myprog test.c library.c

But I don't want to do that either. My library functions should be readily available without needing to include in compile line. According to the same answer, I could create a library and then link to it with -l switch. But when it comes to functions like printf, you don't need to do either of them. All you have to do is to include the header files.Is there any way of doing that?

summary for TL;DR

I want to write a library in C which:

  1. Doesn't have to be implemented in the header file itself.

  2. Doesn't have to be included in the compile line every time I use the library functions.

  3. Doesn't have to be linked with -l every time I use the library function.

  4. Basically the library should be used by only including the header file.

Is there anyway that I could do it in Linux?

Upvotes: 1

Views: 149

Answers (1)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726987

But when it comes to functions like printf, you don't need to do either of them. All you have to do is to include the header files.Is there any way of doing that?

Short answer is "no". Long answer is that C compiler links some libraries "for free", including the library that implements printf.

You have an option to decline these "freebies" - in gcc it's -nodefaultlibs. If you add this option, printf would be missing.

Note: One thing that headers can implement is macros. However, macros do not behave like normal functions, so you should approach them with great caution.

Upvotes: 2

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