# [texhax] [solved] Re: Issue about `~' character

David Carlisle d.p.carlisle at gmail.com
Fri Sep 30 21:40:24 CEST 2016

```On 30 September 2016 at 20:32, Rodolfo Medina <rodolfo.medina at gmail.com> wrote:
> David Carlisle <d.p.carlisle at gmail.com> writes:
>
>> On 30 September 2016 at 19:31, Rodolfo Medina <rodolfo.medina at gmail.com> wrote:
>>> David Carlisle <d.p.carlisle at gmail.com> writes:
>>>
>>> Fantastic, that works in my case.  In this case you need three \string s.  I
>>> couldn't imagine.  I had tried with two.
>>
>> don't think of it as three \string, its, just two tokens each preceded
>> by \string so it gets written verbatim.
>> You want your input file to have
>>
>> \string
>> ~
>> so to write that you can put \string before each token
>>
>> \sting\string
>> \string~
>>
>>
>> so it just more or less coincidentally ends up with three adjacent \string
>
>
> I seem to understand...  Then when I put two \string 's before `~' what
> happened?  How did TeX read and expand that?

\string\string

writes \string to the file and then ~ just writes what it would have
written anyway as it isn't prefixed by anything so you get

\string\penalty \@M \

so when you read that back  the \string applies to \penalty so it
typesets \penalty then quibbles about \@M unless you are in math mode.

David

>
> Thanks,
>
> Rodolfo
>
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