warning: unknown escape sequence '\)'

warning: unknown escape sequence '\)'

[kabir.patel]

I used to have a piece of c code that compiled fine. I now get the follwing
error message with the GNU compiler:

 warning: unknown escape sequence '\)'

The line that it references is:

 fprintf(stream_FND_Resevoir_ctl, "\)\n");

I do not fully understand this (I didn't write the code).

Can somebody tell me:
a) What "\)\n" means?
b) Why it isn't compiling now?
b) If it can be validly replaced?

Thanks in advance


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Re: warning: unknown escape sequence '\)'

[Rupert Wood]

Kabir Patel wrote:

>  warning: unknown escape sequence '\)'

Backslash is used as an escaping character for C strings; if you'd like
to include a character that you wouldn't normally be able to represent
in a text file then you can use an escape code for it, for example:

    \t    tab (ASCII 9)
    \n    newline (ASCII 10)
    \r    carriage return (ASCII 13)
    \001  character with octal value 001
    \xAB  character with hexadecimal value AB

but since backslash has been overloaded, an escape is necessary to
actually embed a backslash:

    \\    backslash

Now there is no '\)' escape defined in C; however, ')' can be escaped in
sed/perl/etc. regular expressions to change its meaning. By default (I
think), an unrecognised escape code will just emit the escaped character
without the escaping backslash, i.e. this will be treated as ')' here.

> a) What "\)\n" means?

Presumably it means a short string: right close bracket, end of line (+
string terminating nul).

> b) Why it isn't compiling now?

It is. That was just a warning; unless you've also specified -Werror
(treat warnings as errors) then this won't stop compilation.

> b) If it can be validly replaced?

Yes, ")\n" is probably correct.

Rup.