[Tex/LaTex] Checking if a number is a multiple of 4

calculationsconditionalsetoolbox

Using etoolbox, ifthen, or another form of conditional checking, how can I check if a value is a multiple of 4? E.g. if the number is 4, 8, 12, 16, etc., then it returns "true".

Best Answer

You can use pgfmath for this:

\documentclass{article}
\usepackage{pgf}

\begin{document}
\newcommand\ifismultiple[4]{%
    \pgfmathparse{mod(#1,#2)==0}
    \ifnum \pgfmathresult=1
    #3%
    \else
    #4%
    \fi
}
\ifismultiple{15}{4}{true}{false}
\end{document}

Related Solutions

[Tex/LaTex] How to undo an etoolbox patch

First of all note that \BeforeBeginEnvironment and \AfterEndEnvironment does not patch the environment itself. It only adds material to hooks. etoolbox patches usage of these hooks to \begin and \end. That's the reason why resetting \itemize and \enditemize to their original definitions does not change anything.

But you may simply undefine the environment end hook of itemize:

\documentclass{article}
\usepackage{etoolbox}
\AfterEndEnvironment{itemize}{bleat bleat}
\begin{document}
\begin{itemize}
\item This is an item.
\end{itemize}

\csundef{@afterend@itemize@hook}% undefine the end hook of itemize
\begin{itemize}
\item This is another item.
\end{itemize}
\end{document}

\csundef is a etoolbox command and \@afterend@itemize@hook is the environment end hook of environment itemize. The environment begin hook would be \@beforebegin@itemize@hook.

Maybe a feature request for commands like \CleanBeforeBeginEnvironment or \CleanAfterBeginEnvironment could be suggested.

Alternative: If you only want to remove something but not everything, you may try this:

\documentclass{article}
\usepackage{etoolbox}

\newrobustcmd*{\RemoveFromAfterEndEnvironment}[2]{%
  \expandafter\patchcmd\csname @afterend@#1@hook\endcsname{#2}{}%
}

\AfterEndEnvironment{itemize}{bleat bleat\par}{}{}
\AfterEndEnvironment{itemize}{don't remove this\par}{}{}
\begin{document}
\begin{itemize}
\item This is an item.
\end{itemize}

\RemoveFromAfterEndEnvironment{itemize}{bleat bleat\par}{}{}
\begin{itemize}
\item This is another item.
\end{itemize}
\end{document}

The third and fourth arguments of \RemoveFromAfterEndEnviroment are the same like third and fourth arguments of \patchcmd.

[Tex/LaTex] Checking if two conditionals are met

You can use the logical combination and and or in the test \ifboolexpr

\ifboolexpr{%
    test {\ifnumless{a}{b}} 
    and
    test{\ifnumgreater{x}{100}}
   }{YES}{NO}

For more details see the documentation (section 3.6.5).

I want to show an example.

\documentclass{article}
\usepackage{etoolbox}
\newcounter{a}\newcounter{b}\newcounter{x}
\newrobustcmd*\setabx[3]{%
  \setcounter{a}{#1}\setcounter{b}{#2}\setcounter{x}{#3}%
}

\newrobustcmd*\iftwocont{%
  \ifboolexpr{%
    test {\ifnumless{\value{a}}{\value{b}}} 
    and
    test{\ifnumgreater{\value{x}}{100}}%
  }%
}
\begin{document}
\setabx{1}{1}{1}
\iftwocont{$a<b$ and $x>100$}{The logical combination is false}

\setabx{5}{10}{300}
\iftwocont{$a<b$ and $x>100$}{The logical combination is false}
\end{document}

Result:

The logical combination is false
a < b and x > 100

Best Answer

Related Solutions

[Tex/LaTex] How to undo an etoolbox patch

[Tex/LaTex] Checking if two conditionals are met

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