When your question is answered use !solved to mark the question as resolved.
Remember to ask specific questions, provide necessary details, and reduce your question to its simplest form. For tips on how to ask a good question run !howto ask.
#hgdassdfas
hybrid coyoteBOT
surreal blade
hybrid coyoteBOT
@cold ice Has your question been resolved? If so, run !solved :)
hoary yewBOT
faint gust
See how errno expands to (*__errno_location ())
Here errno is a macro that expands to a function call, rather than just being a variable
Not something you have to worry about though. Just an implementation detail.
You can print the value of errno
;compile -lm
#include <math.h>
#include <stdio.h>
#include <errno.h>
int main() {
printf("%d\n", errno);
double x = log(-1);
printf("%d\n", errno);
}
errno.h isn't a library
It's a header file that contains the definition of errno, and is part of the C standard library
#include <errno.h> provides the definition of errno that is needed to read the errno set by other standard library functions
Correct
Under the hood it will #include <errno.h> though
Because #include <errno.h> is how you access errno
faint gust
Under the hood it will `#include <errno.h>` though
(or similar, maybe the library implementation internally has a special way to access errno)
Maybe, maybe not
Maybe internally in the .c files that contain definitions for stdio.h functions
If you'd like to learn more, you can read standard library code
here
And you'll notice immediately on line 18, #include <errno.h>
It's not declared internally in stdio.h
It's declared in errno.h, but in some implementations stdio.h could #include errno.h or likely the .c files that contain definitions for stdio.h functions will #include errno.h
errno.h https://codebrowser.dev/glibc/glibc/include/errno.h.html includes stdlib/errno.h https://codebrowser.dev/glibc/glibc/stdlib/errno.h.html which defines it as a macro on line 38
hybrid coyoteBOT
hybrid coyoteBOT
<@undefined>