[tex-k] TeXbook: wrong test when * has catcode 10

Igor Liferenko igor.liferenko at gmail.com
Wed Oct 25 12:58:31 CEST 2023

Hi, all

On p.377 of TeXbook it is said that when * has catcode 10,
the test


is false.

But in this case * is simply ignored during tokenization.
It can be confirmed by adding another \fspace after *:


We get TRUE. If * were not ignored, we would get FALSE.

The test can be corrected by simply putting the * in braces,
i.e., \if\fspace* should be changed into \if\fspace{*}

    \uccode` =`* \uppercase{\uppercase{\def\fspace{ }\let\ftoken= } }


More information about the tex-k mailing list.