Location of library functions' implementations

Well I've been curious for a while as to where I can find the file(s) which show the actual implementation of library functions such as atoi(const char *str). I found the stdlib.h header file, but all that it contained was external declarations of all its functions:

Code:

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...
extern double complex atoc(const char *);
extern double atof(const char *);
extern int atoi(const char *);
extern long int atol(const char *);
...

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Then, using a debugger, I found that the atoi function actually led to another file, atoi.chf, which only used another library function, strtol(const char *str, char **endptr, int base), to make the conversion. The debugger, however, would not step into that function, so I could not find its source.

Does anyone know if/where I can find the inner workings of these functions?

Note: I'm using a C/C++ interpreter, Ch, on Windows 7. All of the files I found are within the C:\Ch directory.

That code is usually pre-compiled and linked in a shared library by the time you get to use it so you cant jump to it unless you are prepared to read it in assembler.

Try have a look at libc (GNU C Library - GNU Project - Free Software Foundation (FSF)), that has good implementations if you want to have a look at how the functions work

thanks for the quick response! :)
hmm oh yea I remember about that now that you mention it - pre-processing -> compiling -> assembly -> linking

well do you know where I can find the assembly file?

Usually you add an option to the compiler command line to generate either a listing file or assembler output for the files you're compiling. This still won't show ASM code for the libraries. There you need a tool to disassemble the libraries - depending on lots of factors this can be easy or difficult to do. What are you using to compile - compiler, OS, and so on.

Quote:

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Originally Posted by LanguidLegend

thanks for the quick response! :)
hmm oh yea I remember about that now that you mention it - pre-processing -> compiling -> assembly -> linking

well do you know where I can find the assembly file?

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Did you try libc? There are C versions of the functions you mentioned in the download

Quote:

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Originally Posted by LanguidLegend

thanks for the quick response! :)
hmm oh yea I remember about that now that you mention it - pre-processing -> compiling -> assembly -> linking

well do you know where I can find the assembly file?

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If you're looking for library source code, most often it's not available except directly from the library's authors... and usually at a fee.

There are "library like" source codes, as Fordy points out, that can be downloaded. But these will not be the exact source of your library.

Quote:

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Originally Posted by Fordy

Did you try libc? There are C versions of the functions you mentioned in the download

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I tried looking on the GNU C Library website, but couldn't find a list of library functions. Could you link me to a list or just to the atoi function page?

Thanks!

http://ftp.gnu.org/gnu/glibc/glibc-2.14.tar.gz

Download it...decompress it...look at what's inside

Quote:

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Originally Posted by LanguidLegend

I tried looking on the GNU C Library website, but couldn't find a list of library functions. Could you link me to a list or just to the atoi function page?

Thanks!

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The GNU C Library - GNU Project - Free Software Foundation (FSF)