I have some string in variable \somevar, eg. foo\\bar. How can I force LaTeX to ignore newline in \somevar. When I write content of the variable there should be
foo bar
and not
foo bar
[Tex/LaTex] Ignore newline in LaTeX variable
tex-core
Related Solutions
A token register is very similar to a macro with no arguments, but there are differences in syntax and expansion rules.
Using the plain and latex definition of \toks@ for \toks 0 you can store the tokens abc via
\toks@{abc}
or
\def\tmp{abc}
Note that a macro has a specific command to set the macro (\def or wrappers around that such as \newcommand) but token registers just use the register name followed by a balanced text group.
Conversely unlike macros which expand just by referencing their name, token registers, like other registers, are not expandable and their contents are accessed by expanding \the.
So
\the\toks@
and
\tmp
each expand to abc.
Apart from these syntactic differences the expansion of token registers differs from macros in two important ways.
expansion in
\edefand other expansion only contexts is limited to one level:\def\tmp{aaa} \def\tmpb{xx \tmp} \toks@{xx \tmp} \edef\A{\tmpb} \edef\B{\the\toks@}Now
\tmpband\toks@contain the same token listxx \tmpbut\Ais defined by fully expanding expandable tokens and so has defnitionxx aaabut the tokens returned by\theare not further expanded in the\edefand so\Bhas definitionxx \tmpThe second difference is that as token registers do not have arguments
#does not need to be (and is not) special when defining or expanding the register.\toks@{#1}is just a token register consisting of a list of two tokens
#and1.
This is put to use in LaTeX's \g@addto@macro macro.
\g@addto@macro@\foo{abc}
is supposed to add abc to the end of the current definition of \foo.
A simple (and if I recall correctly original) definition could be
\makeatletter
\gdef\foo{123}
\def\gaA#1#2{%
\expandafter\gdef\expandafter#1\expandafter{#1#2}}
\gaA\foo{abc}
\show\foo
That works fine and shows the definition as 123abc. However try
\gaA\foo{#}
and you get
! Illegal parameter number in definition of \foo.
However we can use the fact that # isn't special in a toks register and that the register contents are only expanded once
\long\def\g@addto@macro#1#2{%
\begingroup
\toks@\expandafter{#1#2}%
\xdef#1{\the\toks@}%
\endgroup}
First the \toks@ register is defined to contain the expansion of the macro passed in the first argument, followed by the contents of the second argument. # is safe to use in a toks assignment. Then the macro is globally defined to be the expansion of \thetoks which is exactly the contents of \toks@ with no further expansion, even if that contains # tokens:
\makeatletter
\gdef\foo{123}
\g@addto@macro\foo{abc}
\show\foo
\g@addto@macro\foo{#}
\show\foo
produces
> \foo=macro:
->123abc.
l.7 \show\foo
?
> \foo=macro:
->123abc##.
l.11 \show\foo
where # has been added as intended (only one # has been added, the doubled ## is an artefact of using \show).
Using \pgfmathtruncatemacro makes the trick.
\documentclass{standalone}
\usepackage{amsmath,tikz}
\usetikzlibrary{arrows,calc}
\begin{document}
\begin{tikzpicture}
\def \currentYear {2016}
\def \n {4}
\foreach \i in {0,...,\n}
{
\pgfmathtruncatemacro{\nextYear}{\currentYear + \i}
\node (N) at (\i,\i) {\nextYear};
}
\end{tikzpicture}
\end{document}
Best Answer
Within the group that you are expanding the macro you can do
This will temporarily neuter the effect of
\\.