\foreach 在记忆部分中对“最初”参数存在问题

Question

我的代码中是否有错误，或者我发现了一个错误？如果有，\foreach语句似乎不会增加，但它可以与手动给定的初始值（）一起使用。\lastninitally (value)\def\lastn

这是我所期望的……

…这就是我得到的……

这是我的 MWE：

\documentclass[border=1cm]{standalone}

\usepackage{tikz}

\begin{document}
\begin{tikzpicture}[every node/.style={draw}]
    \node (A) at (0,0) {A};
    \node (B) at (2,0) {B};
    \node (C) at (4,0) {C};
    \node (D) at (6,0) {D};
%   DOESN'T WORK
%   \foreach \n [remember=\n as \lastn (initially A)] in {B,C,D} {
%       \draw [->] (\lastn) -- (\n);
%   }
%   WORKS
    \def\lastn{A}
    \foreach \n [remember=\n as \lastn] in {B,C,D} {
        \draw [->] (\lastn) -- (\n);
    }
\end{tikzpicture}
\end{document}

Answer 1

它适用于\newforeach：

\documentclass[border=1cm]{standalone}
\usepackage{tikz}
\usepackage{loops}
\begin{document}
\begin{tikzpicture}[every node/.style=draw]
\node (A) at (0,0) {A};
\node (B) at (2,0) {B};
\node (C) at (4,0) {C};
\node (D) at (6,0) {D};
\newforeach \n [remember=\n as \lastn initially A] in {B,C,D}
  \draw [->] (\lastn) -- (\n);
\end{tikzpicture}
\end{document}

您也可以尝试

\documentclass[border=1cm]{standalone}
\usepackage{tikz}
\usepackage{loops}
\begin{document}
\begin{tikzpicture}
\node at (0,1) [circle,draw,red] {
  \foxloop [remember=#1 as \x initially A] {B,C,D,E,F,G,H}{%
    $\overrightarrow{\x#1}$\iflastfox.\else,\space\fi
  }
};
\end{tikzpicture}
\end{document}