Sunday, July 10, 2022

[SOLVED] Regular expression to extract header name from c file

Issue

How to extract headers from a c file that contains them like this?

#include <tema4header9.h>
#include    <tema4header3.h>
#include   <stdio.h>
#include        <longnametest/newheader.h>
#include <net/header.h>
#include  "last-test-Zhy3/DrRuheader.h"
#include <last-test-8fF7/a5xyheader.h>

I tried to use:

sed -n -e 's/#include[ \t]*[<"]\([^ \/<"]*\/[^ \/]*\)\.h[">]/\1\.h/p'

but it only works for those in subdirectories. also if i type:

sed -n -e 's/#include[ \t]*[<"]\(([^ \/<"]*\/)+[^ \/]*\)\.h[">]/\1\.h/p'

or

sed -n -e 's/#include[ \t]*[<"]\(([^ \/<"]*\/)*[^ \/]*\)\.h[">]/\1\.h/p'

the command does not work anymore. The output file should look like this:

tema4header9.h
tema4header3.
stdio.h
longnametest/newheader.h
net/header.h
last-test-Zhy3/DrRuheader.h
last-test-8fF7/a5xyheader.h

Solution

grep solution: This is using perl regex and printing anything between "<" or '"' on the lines which start with #include. 

grep -oP '^#include.*(<|")\K.*(?=>|")' headers
tema4header9.h
tema4header3.h
stdio.h
longnametest/newheader.h
net/header.h
last-test-Zhy3/DrRuheader.h
last-test-8fF7/a5xyheader.h

If you are ok with awk: 

awk '/#include/{gsub(/<|>|"/,"",$2);print $2}' headers
tema4header9.h
tema4header3.h
stdio.h
longnametest/newheader.h
net/header.h
last-test-Zhy3/DrRuheader.h
last-test-8fF7/a5xyheader.h


Answered By - P....
Answer Checked By - Dawn Plyler (WPSolving Volunteer)
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