## ASP.NET RadioButtonList CellSpacing Property
The `CellSpacing` property is a member of the `RadioButtonList` control in ASP.NET Web Forms. It is used to get or set the spacing (in pixels) between individual cells in the rendered table layout of the radio button list.
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### Definition and Usage
The `CellSpacing` property defines the amount of space between the cells of the table that contains the radio buttons.
> **Important Note:** This property is only effective when the `RepeatLayout` property of the `RadioButtonList` is set to `RepeatLayout.Table` (which is the default layout behavior). If `RepeatLayout` is set to `Flow`, `UnorderedList`, or `OrderedList`, this property will be ignored because no HTML `
` element is generated.
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### Syntax
```xml
```
#### Property Values
| Value | Description |
| :--- | :--- |
| `pixels` | An integer representing the number of pixels of space between the table cells. |
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### Code Example
The following example demonstrates how to set the `CellSpacing` property to `15` pixels to create visible separation between the radio button options.
#### ASPX Markup:
```xml
<%@ Page Language="C#" %>
RadioButtonList CellSpacing Example
```
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### Key Considerations
1. **Layout Dependency**: Always ensure `RepeatLayout` is set to `Table` (or left omitted, as it defaults to `Table`) when using `CellSpacing`.
2. **CellPadding vs. CellSpacing**:
* `CellSpacing` controls the space *between* adjacent cells.
* `CellPadding` controls the space between the *cell border* and the *cell content* (the radio button and its label).
3. **Modern Web Standards**: While `CellSpacing` is a quick way to style layout in legacy Web Forms applications, modern web development often favors using CSS (e.g., `gap` in Flexbox/Grid or `margin` on list items) combined with `RepeatLayout="Flow"` or `RepeatLayout="UnorderedList"` for cleaner, responsive HTML output.
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