Write the shell / sed program which remove all the comments from a simple C program stored in your current directory. You can assume that the c source code contains only syntactically correct comments:
+ start with // and end with a newline
+ starting with /* and ending */ (can be multiline)
+ nesting of comments is not allowed
Make sure that C source is not changed at all.
How do I use this sed script?
$ ./script.sed < input.c
$ ./script.sed < input.c > output.c
$ for c in *.c; do script.sed < $c > /tmp/zyzcc.c; /bin/cp -f /tmp/zyzcc.c $c; done
Sample sed code to remove all comments from sed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 | #! /bin/sed -nf # Remove C and C++ comments, by Brian Hiles (brian_hiles@rocketmail.com) # Sped up (and bugfixed to some extent) by Paolo Bonzini (bonzini@gnu.org) # Works its way through the line, copying to hold space the text up to the # first special character (/, ", '). The original version went exactly a # character at a time, hence the greater speed of this one. But the concept # and especially the trick of building the line in hold space are entirely # merit of Brian. :loop # This line is sufficient to remove C++ comments! /^\/\// s,.*,, /^$/{ x p n b loop } /^"/{ :double /^$/{ x p n /^"/b break b double } H x s,\n\(.[^\"]*\).*,\1, x s,.[^\"]*,, /^"/b break /^\\/{ H x s,\n\(.\).*,\1, x s/.// } b double } /^'/{ :single /^$/{ x p n /^'/b break b single } H x s,\n\(.[^\']*\).*,\1, x s,.[^\']*,, /^'/b break /^\\/{ H x s,\n\(.\).*,\1, x s/.// } b single } /^\/\*/{ s/.// :ccom s,^.[^*]*,, /^$/ n /^\*\//{ s/..// b loop } b ccom } :break H x s,\n\(.[^"'/]*\).*,\1, x s/.[^"'/]*// b loop |
Please note that this program is copied from public domain.