Detecting and skipping line comments with Flex

Question

How can I detect one line comments like // in Flex and skip those lines?

Also, for /* comments, will the following snippet be enough?

Answer 1

To detect single line comments :

^"//"    printf("This is a comment line\n");

This says any line which starts with // will be considered as comment line.

To detect multi line comments :

^"/*"[^*]*|[*]*"*/" printf("This is a Multiline Comment\n");

*

Explanation :

*

^"/*" This says beginning should be /*.

[^*]* includes all characters including \n but excludes *.

[*]* says 0 or more number of stars.

[^*]|[*]* - "or" operator is applied to get any string.

"*/" specifies */ as end.

This will work perfectly in lex.

Below is the complete code of lex file :

%{
#include 
int v=0;
%}
%%
^"//"    printf("This is a comment line\n");
^"/*"[^*]*|[*]*"*/" printf("This is a Multiline Comment\n");
.|\n {}
%%
int yywrap()
{
    return 1;
}
main()
{
    yylex();
}