> 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-tw/latex-cuo-wu/30-there-were-undefined-references.md).

# 有未定義的參考

當 **`\ref{...}`** 被使用，而 LaTeX 無法找到對應的標籤時。這種情況可能有三種原因。

* 在……中有拼字錯誤 **`\label{...}`**
* 在……中有拼字錯誤 **`\ref{...}`**
* 有一個標籤被遺漏了。

下面顯示一個範例

```latex
\section{introduction}\label{introduction}
引用 introduction 時若有拼字錯誤，會像 \ref{intorduction} 這樣。

另一個錯誤是引用一個從未定義過的標籤，例如 \ref{section1}
```

這些都會產生如下所示的錯誤

main.tex，第 6 行

第 1 頁上的參照 \`intorduction' 在輸入第 6 行未定義。

main.tex，第 6 行

第 1 頁上的參照 \`section1' 在輸入第 8 行未定義。

main.tex，第 6 行

存在未定義的參照。

為了避免這種情況，我們必須始終確保當我們使用 **`\ref{...}`**時，都有對應的 **`\label{...}`**，且 **`\ref{...}`** 和 **`\label{...}`** 是一樣的。


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