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循环计数器未被解释为数字

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循环计数器未被解释为数字

我想创建 32 个彼此相邻的小框，每个小框包含其当前索引。

|0|1|2|3|.​​..|31|

这段代码让我很麻烦：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning}

\begin{document}

\begin{tikzpicture}[
    node distance=0pt, 
    box/.style={outer sep=0pt, draw, thick, minimum height=0.6cm}]

    \node[box](0) {0};

    \foreach \i in {0, 31} {                
        \node[box, right=of \i] (\i + 1) {\i+1};    
    }

    \end{tikzpicture}
\end{document}

我的印象是 {\i+1} 未被解释，而是实际上为给定的 i 写入了 i+1。我怎样才能让 tikz 计算 i+1 并将结果指定为名称或标签？

答案1

是的，你的印象是对的。强制求值的一种方法是使用\numexpr。

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning}

\begin{document}

\begin{tikzpicture}[
    node distance=0pt, 
    box/.style={outer sep=0pt, draw, thick, minimum height=0.6cm}]

    \node[box](0) {0};

    \foreach \i in {0,..., 31} {                
        \node[box, right=of \i] (\the\numexpr\i + 1\relax)
        {\the\numexpr\i+1\relax};    
    }

    \end{tikzpicture}
\end{document}

不过，不太复杂的方法是使用评估。

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{positioning}

\begin{document}

\begin{tikzpicture}[
    node distance=0pt, 
    box/.style={outer sep=0pt, draw, thick, minimum height=0.6cm}]

    \node[box](0) {0};

    \foreach \i [evaluate=\i as \nexti using {int(\i+1)}] in {0,..., 31} {                
        \node[box, right=of \i] (\nexti)
        {\nexti};    
    }

    \end{tikzpicture}
\end{document}

在此处输入图片描述

这是pic其一个版本。

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{positioning}

\begin{document}

\begin{tikzpicture}[
    node distance=0pt, 
    box/.style={outer sep=0pt, draw, thick, minimum height=0.6cm},
    pics/boxrow/.style 2 args={code={
    \node[box] (#1){#1};
    \foreach \i [evaluate=\i as \nexti using {int(\i+1)}] in
    {#1,\the\numexpr#1+1,...,#2} {                
        \node[box, right=of \i] (\nexti)     {\nexti};    
    }
    }}]
 \path (0,0) pic{boxrow={0}{30}}
 (0,-1) pic{boxrow={5}{18}};
\end{tikzpicture}
\end{document}

在此处输入图片描述

答案2

甚至还有另一种解决方案：

\documentclass[tikz, border=2mm]{standalone}
\usetikzlibrary{positioning}

\begin{document}

\begin{tikzpicture}[
    node distance=0pt, 
    box/.style={outer sep=0pt, draw, thick, minimum height=0.6cm}]

    \node[box](0) {0};

    \foreach \i [remember=\i as \lasti (initially 0), count=\ni] in {1, ..., 31} {                
        \node[box, right=of \lasti] (\ni) {\ni};    
    }

    \end{tikzpicture}
\end{document}

在此处输入图片描述

答案3

变体Ignasi 的回答您可以轻松更改范围的上限和下限\foreach。

\documentclass[tikz, border=2mm]{standalone}
\usetikzlibrary{positioning}

\begin{document}

\begin{tikzpicture}[
  node distance=0pt, 
  box/.style={outer sep=0pt, draw, thick, minimum height=0.6cm}
]
  \foreach \i [remember=\i as \lasti (initially a)] in {0, ..., 31} {
    \if a\lasti
      \node[box](\i) {\i};
    \else
      \node[box, right=of \lasti](\i) {\i};
    \fi
  }
\end{tikzpicture}
\end{document}

答案4

一个更简单的解决方案是重复使用名称。

\documentclass{standalone}% too big for article
\usepackage{tikz}
%\usetikzlibrary{positioning}% not needed

\begin{document}

\begin{tikzpicture}[
    node distance=0pt, 
    box/.style={outer sep=0pt, draw, thick, minimum height=0.6cm}]

    \node[box](0) {0};
    \coordinate (last) at (0.east);

    \foreach \i in {1, ..., 31} {                
        \node[box, right] (\i) at (last) {\i}; 
        \coordinate (last) at (\i.east);
    }

    \end{tikzpicture}
\end{document}

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