Question

I’m using SED to remove C-Style comments.

Here is the command I’m using:

sed s:[/][*].*[*][/]::g

There 2 cases I can’t figure out:

First:

int x /* comment */ = 1; /* comment */ 

output:
int x

Second: multi-line comment

/* first line 
   second line */

Output:

/* first line
   second line */

The first problem is with the .* in the middle as the pattern matching is greedy and once the first “/” is matches [/][*], the inner comment expression match . and the ending comment expression matches the ending the [*][/].

Now the problem with the second is “.” doesn’t match new line character but if i put a new line character the following thing happens.

input:

int x;
/* comment */
x = 1;
/* comment */

output:

int x;

Can some tell me how to make closing tags are matched not consumed by .* or [\s\S]*?

Answer 1

This is one Regex I could come up with : \/\*(.*?)\*\/

Input :

`int x /* comment */ = 1; /* comment */ 
/* first line 
   second line */
int x;
/* comment */
x = 1;
/* comment */`

Output is:

$matches Array:
(

    [0] => Array
        (
            [0] => /* comment */
            [1] => /* comment */
            [2] => /* first line second line */
            [3] => /* comment */
            [4] => /* comment */
        )

    [1] => Array
        (
            [0] =>  comment 
            [1] =>  comment 
            [2] =>  first line second line 
            [3] =>  comment 
            [4] =>  comment 
        )

)