Manipulating arguments in newcommand

Question

I'd like to manipulate the arguments in \newcommand. More explicitly, I'd like something like that:

\newcommand{\X}[1]{
#1+1
}

And if I call \X{0}, I want it to return 1 and not 0+1.

Thank you :-)

Answer 1

This is the first time I tried \numexpr as suggested by percuße in comment. I have added \pgfmathparse as another possibility.

\documentclass[10pt]{article}

\usepackage{tikz}

\newcommand{\X}[1]{%
\pgfmathparse{int(#1+1)}\pgfmathresult%
}

\newcommand{\XX}[1]{%
\number\numexpr#1+1\relax%
}

\begin{document}
\X{0}
\begin{enumerate}
\foreach \x in {0,...,5}
    {\item \X{\x}}
\end{enumerate}
\XX{0}
\begin{enumerate}
\foreach \x in {0,...,5}
    {\item \XX{\x}}
\end{enumerate}
\end{document}

Note that you can also change \pgfmathparse{#1+1}\pgfmathresult into \pgfmathparse{int(#1+1)}\pgfmathresult if you want to remove the decimals.