> For the complete documentation index, see [llms.txt](https://overleaf-pro.ayaka.space/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://overleaf-pro.ayaka.space/latex/zh-cn/latex-cuo-wu/22-misplaced-noalign.md).

# \noalign 放置位置不当

当你使用了 **`\hline`** 不正确地。

## 常见原因

**在表格外使用 \hline：**

该 **`\hline`** 该命令只能在一个 **`tabular`** 环境中使用。你不能用它在文档的其他位置插入水平线，例如标题页或页眉。这个错误的一个示例如下：

```latex
%在导言区
\title{论热的普遍分子理论}
\author{A. 爱因斯坦}

% 在文档正文中
\maketitle

\hline
```

这将产生如下所示的错误

main.tex，第 5 行

\noalign 放置位置不当。

\hline ->\noalign {\ifnum 0=\`}\fi \hrule \\@height \arrayrulewidth \futurelet... l.10 \hline 我只希望在对齐环境的 \cr 之后才看到 \noalign。继续吧，我会忽略这种情况。

当你想在 tabular 环境之外插入水平线时，你必须使用 **`\hrule`**.

**在表格中错误地使用 \hline：**

在使用 **`\hline`** 在表格中，除第一处外，每一处之前都必须加上 **`\\`**。下面展示了这个错误的一个示例

```latex
\begin{tabular}{|l|l|} \hline
    名字：& Albert \\ \hline
    第二个姓名：& 爱因斯坦 \hline
\end{tabular}
```

第一个 **`\hline`** 此处的命令没有问题，因为第一处 **`\hline`** 在表格中不需要在其前面加上 **`\\`**。问题在于我们的最后一个 **`\hline`** 它之前确实需要加上 **`\\`**。这个表格的正确写法是：

```latex
\begin{tabular}{|l|l|} \hline
    名字：& Albert \\ \hline
    第二个姓名：& 爱因斯坦 \\ \hline
\end{tabular}
```

![Table.PNG](/files/604163afdf037bf25c73df722dc9333f0c581c8c)


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