> 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/wen-da/66-i-m-trying-to-include-urls-in-my-.tex-or-.bib-but-i-got-an-error-missing-inserted.md).

# 我试图在 .tex 或 .bib 中包含 URL，但出现了错误“Missing $ inserted”

您的 URL 可能包含一些下划线字符 `_`，它们是 LaTeX 中的特殊字符——在数学模式下它们是下标运算符，例如 `$x_i$` 会生成 $$x\_i$$。通常，如果你想在普通文本中使用字面下划线字符，你需要将其转义为 `\_`.

不过，包含下划线的 URL 还有一种更简单的写法。如果你添加 `\usepackage{url}` 或 `\usepackage{hyperref}` 之前写上 `\begin{document}`，然后你就可以写：

```latex
\url{https://www.example.com/url_with_underscore}
```

到你的文档中。

有关更多详情，请参阅 Overleaf 帮助文章 [插入了缺少的 $](/latex/zh-cn/latex-cuo-wu/25-missing-inserted.md).


---

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