How can I delete all /* */ comments from a C source file?

awk, perl, regex, sed, unix

Solution

Why not just use the c preprocessor to do this? Why are you confining yourself to a home-grown regex?

[Edit] This approach also handles Barts `printf(".../*...")` scenario cleanly

Example:

[File: t.c]
/* This is a comment */
int main () {
    /* 
     * This
     * is 
     * a
     * multiline
     * comment
     */
    int f = 42;
    /*
     * More comments
     */
    return 0;
}

.

$ cpp -P t.c
int main () {







    int f = 42;



    return 0;
}

Or you can remove the whitespace and condense everything

$ cpp -P t.c | egrep -v "^[ \t]*$"
int main () {
    int f = 42;
    return 0;
}

No use re-inventing the wheel, is there?

[Edit] If you want to not expand included files and macroa by this approach, `cpp` provides flags for this. Consider:

[File: t.c]

#include <stdio.h>
int main () {
    int f = 42;
    printf("   /*  ");
    printf("   */  ");
    return 0;
}

.

$ cpp -P -fpreprocessed t.c | grep -v "^[ \t]*$"
#include <stdio.h>
int main () {
    int f = 42;
    printf("   /*  ");
    printf("   */  ");
    return 0;
}

There is a slight caveat in that macro expansion can be avoided, but the original definition of the macro is stripped from the source.

Problem

I have a C file which I copied from somewhere else, but it has a lot of comments like below: ``` int matrix[20]; /* generate data */ for (index = 0 ;index < 20; index++) matrix[index] = index + 1; /* print original data */ for (index = 0; index < 5 ;index++) ``` How can I delete all the comments enclosed by `/*` and `*/`. Sometimes, the comments are consist of 4-5 lines, and i need to delete all those lines. Basically, I need to delete all text between `/*` and `*/` and even `\n` can come in between. Please help me do this using one of `sed`, `awk` or `perl`.

Original source