[texhax] Issue about `~' character

[Rodolfo Medina]

Philip Taylor <P.Taylor at Rhul.Ac.Uk> writes:

> Rodolfo Medina wrote:
>
>> I need to use the `~' character within an internet address so I want TeX not
>> to use it as it usually does, i.e. doing nothing but prevent breaking.
>> Putting `\string~' does not help because that character occurs within an
>> \openout... \write... \closeout environment.  How could I do?
>
> The problem will not occur when writing but when reading it back, at which
> point it will once again have its normal \catcode.  Either change the catcode
> before reading the file, or express it as \char `\~


Thanks.  But I don't exactly know how to do what you suggest.  I tried with:

 \catcode`~ = 12

before reading the file, but it had no effect.  Also I put

 \char`\~

in place of

 ~
but didn't work either.  Please let me more specifically understand...

Thanks,

Cheers,

Rodolfo