TikZ: Variable arithmetic result in node name

Question

I'm having trouble incrementing a variable in TikZ and then using the result as part of a node name:

\def\x{2}
\begin{figure}[H]
\begin{tikzpicture}
\pgfmathsetmacro{\xplusone}{add(\x,1)}
\node (X\xplusone1) at (0,0) {};
\path (1, 1) edge (X\xplusone1);
\end{tikzpicture}
\end{figure}

seems to be parsing the final line as "X3" instead of "X31".

Answer 1

\pgfmathsetmacro always saves its result with a decimal place, even if you're just working with integers. This will confuse TikZ, which assumes that a period separates a node name from an anchor. You should use \pgfmathtruncatemacro instead, which will discard the decimal digits:

\documentclass{article}
\usepackage{tikz}

\begin{document}

\def\x{2}
\begin{tikzpicture}
\pgfmathtruncatemacro{\xplusone}{\x + 1}
\node (X\xplusone1) at (0,0) {};
\path (1, 1) edge (X\xplusone1);
\end{tikzpicture}

\end{document}