Application of '/' in some header files

Question

Recently I have come across a couple of header files like

 #include <sys/socket.h>
 #include <sys/types.h>
 #include <netinet/in.h>
 #include <bits/stdc++.h>

I wanted to know the actual reason as to why '/' is used.

So far I have taken it as an operation to include the sub-header file of a bigger header file just like Java

 import java.util.Scanner;

but
If you remove the '/' and try to include the header file as whole
It shows an error that header file doesn't exists.

Kindly clear the confusion regarding this problem.

Thanks in advance.

On second thought that dupe might not be what you are asking. linking it here though. related: http://stackoverflow.com/questions/5790161/is-the-backslash-acceptable-in-c-and-c-include-directives — NathanOliver, Oct 31 '16 at 13:09

score 4 · Answer 1 · answered Oct 31 '16 at 13:06

4

Directory separation. For example, there is a directory sys which has a header file called socket.h.

And as paths in the filesystem, it can be multiple levels. You can have #include <some/sub/directory/with/a/file.h>.

The actually use of slash (/) versus backslash (\) (or anything else really) is not standardized, but is depending on the system. However all major platforms support slash (/) as separators in paths so it's most common.

answered Oct 31 '16 at 13:06

Some programmer dude

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I see , so the first word represented the directory. thank you very much. – Ryuzaki Oct 31 '16 at 13:11
1

Note that strictly speaking, the C++ standard says nothing on how these strings are handled. It just so happens that (nearly?) all compilers currently in use, interpret them as filenames including directories. – rubenvb Oct 31 '16 at 13:15
@Ryuzaki As rubenvb commented, it doesn't really have to be directories. It just makes sense that it is, and that the whole "path" is part of an actual path in a filesystem. – Some programmer dude Oct 31 '16 at 13:19

score 3 · Answer 2 · answered Oct 31 '16 at 13:11

3

Files on your hard drive are organised into directories (or "folders").

The full name of a file is identified by its path, which may name several of these directories, separated by a slash character (/) or a backslash character (\).

Read more here:

answered Oct 31 '16 at 13:11

Lightness Races in Orbit

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The backslash character works only on MS Windows AFAIK, while slash works in whole *NIX world plus the windows support it too. So for source portability reasons I would stay with slash only. – Ped7g Oct 31 '16 at 13:49
@Ped7g: As would I. I am simply explaining what directories are, since the OP doesn't seem to know. – Lightness Races in Orbit Oct 31 '16 at 13:50

score 1 · Answer 3 · answered Oct 31 '16 at 13:25

When you build a c++ file, the preprocessor looks for the files you specified to include in a set of directories (default ones + directories you pass on the command line).

For each #include <something> it tries to open BASE_DIR/something where BASE_DIR is one of the aforementioned directories.

So sys/socket.h denoted the preprocessor should try and delve into the subdirectory sys and open socket.h

Application of '/' in some header files

3 Answers3