Initial Query

In latex when I force a newline in a caption with \\ it gives an error saying \Hy@tempa has an extra } runaway argument?

LLM Generation

Query

In latex when I force a newline in a caption with \\ it gives an error saying \Hy@tempa has an extra } runaway argument?

Output

When using LaTeX to create captions for figures or tables, incorporating line breaks with `\\` can sometimes lead to errors, especially when packages like `hyperref` are involved. The specific error message: 

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\Hy@tempa has an extra } runaway argument
indicates that `hyperref` is having trouble processing the `\\` command within the caption. This is because `hyperref` attempts to use the caption text for PDF bookmarks, and certain LaTeX commands like `\\` can disrupt this process. Here are several solutions to resolve this issue: ### 1. Use `\protect` with `\\` By preceding the `\\` with `\protect`, you inform LaTeX to treat it correctly within the moving arguments (like captions). 
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\caption{First line of caption\protect\\ Second line}
### 2. Use `\newline` Instead of `\\` The `\newline` command is often more compatible in contexts where `\\` causes issues. 
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\caption{First line of caption\newline Second line}
### 3. Provide an Optional Short Caption You can supply an optional argument to `\caption` that excludes the line break. This short caption will be used for the List of Figures/Tables and PDF bookmarks, avoiding the problematic `\\`. 
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\caption[First line of caption. Second line]{First line of caption\\ Second line}
**Explanation:** - The optional argument `[First line of caption. Second line]` serves as a simplified version of the caption without the `\\`, making it safe for `hyperref` to process. - The main argument `{First line of caption\\ Second line}` contains the formatted caption with the line break for display in the document. ### 4. Use the `\newline` Command Within the Optional Argument If you prefer to keep the line break in both the caption and the optional text, you can use `\newline` in the main caption and a simple space or period in the optional caption. 
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\caption[First line of caption. Second line]{First line of caption\newline Second line}
### 5. Utilize the `caption` Package for Enhanced Control The [`caption`](https://ctan.org/pkg/caption) package offers more flexibility and might handle such cases more gracefully. 
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\usepackage{caption}

% Later in the document
\caption{First line of caption\\ Second line}
**Note:** Ensure that the `caption` package is loaded **before** the `hyperref` package to maximize compatibility. ### Summary The error arises because `hyperref` struggles with certain LaTeX commands within captions. By either protecting the line break command, using an alternative like `\newline`, or providing a simplified optional caption, you can resolve the error and achieve the desired formatting in your captions. If problems persist, consider reviewing the order in which packages are loaded in your preamble, as some package interactions can also lead to unexpected errors. --- **Example Implementation:** 
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\documentclass{article}
\usepackage{hyperref}
\usepackage{caption} % Optional, for enhanced caption control

\begin{document}

\begin{figure}[h]
    \centering
    % Your figure here
    \caption[Short caption without line break]{First line of caption\protect\\ Second line}
    \label{fig:example}
\end{figure}

\end{document}
This approach ensures that your captions display correctly in the document while maintaining compatibility with `hyperref` for PDF bookmarks and hyperlinks.

Substring Evaluation

Testing if the previous output contains the string \protect: True

Initial Query

In latex when I force a newline in a caption with \\ it gives an error saying \Hy@tempa has an extra } runaway argument?

LLM Generation

Query

In latex when I force a newline in a caption with \\ it gives an error saying \Hy@tempa has an extra } runaway argument?

Output

When you include a line break (`\\`) directly within a caption in LaTeX, it can cause errors, especially when packages like `hyperref` are involved. This is because captions are "moving arguments" — they are written to auxiliary files for things like lists of figures and cross-references. Fragile commands like `\\` need special handling in these contexts to prevent errors like the one you're encountering: `\Hy@tempa has an extra } runaway argument?` Here are several approaches to resolve this issue: ### 1. Use `\protect\\` By prefixing the line break with `\protect`, you inform LaTeX that the command is fragile and should be handled appropriately within the moving argument. 

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\caption{First line\protect\\ Second line}
### 2. Use `\newline` Instead of `\\` The `\newline` command is often more robust in captions and can serve as a substitute for `\\`. 
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\caption{First line\newline Second line}
### 3. Utilize the `caption` Package The `caption` package provides enhanced control over captions, including easier line breaks and formatting options. First, ensure you've included the package in your preamble: 
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\usepackage{caption}
Then, you can use the `\caption` command with line breaks as follows: 
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\caption{First line\\ Second line}
Alternatively, the `caption` package allows for more advanced formatting, such as setting a specific width for captions and enabling automatic line breaks. ### 4. Define a Custom Command for Line Breaks If you frequently need line breaks in captions, defining a custom command can make your code cleaner: 
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\newcommand{\CaptionLineBreak}{\protect\\}

...

\caption{First line\CaptionLineBreak Second line}
### 5. Ensure Package Compatibility and Updates Sometimes, errors arise from outdated packages or incompatibilities between packages. Make sure that all your packages, especially `hyperref` and `caption`, are up to date. Using a package manager like `TeX Live` or `MiKTeX` can help manage updates efficiently. ### Example Implementation Here's a minimal example demonstrating the use of `\protect\\` within a caption: 
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\documentclass{article}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{hyperref}

\begin{document}

\begin{figure}[h]
    \centering
    \includegraphics[width=0.5\textwidth]{example-image}
    \caption{This is the first line\protect\\ and this is the second line}
    \label{fig:example}
\end{figure}

\end{document}
This should compile without errors, rendering the caption with a line break as intended. ### Summary The key is to ensure that fragile commands like `\\` are properly protected or replaced within moving arguments such as captions. Using `\protect\\`, `\newline`, or leveraging the capabilities of the `caption` package are effective strategies to achieve this. If you continue to experience issues, consider sharing a minimal working example (MWE) of your code, which can help in diagnosing the problem more precisely.

Substring Evaluation

Testing if the previous output contains the string \protect: True