---
id: "P:cAlgo.API.OpenFileDialog.DefaultExt"
kind: "property"
type: "T:cAlgo.API.OpenFileDialog"
url: "https://help.ctrader.com/ctrader-algo/references/Dialogs/OpenFileDialog/DefaultExt/"
---

> Documentation index for agents: https://help.ctrader.com/ctrader-algo/llms.txt · machine index: https://help.ctrader.com/ctrader-algo/api.json

# OpenFileDialog.DefaultExt

Member of [OpenFileDialog](https://help.ctrader.com/ctrader-algo/references/Dialogs/OpenFileDialog/index.md).

## DefaultExt

Gets or sets a value that specifies the default extension string to use to filter the list of files that are displayed.

Environments: Desktop supported · CLI not supported · Cloud not supported.

- CLI: No dialog can be shown in the CLI: ShowDialog returns FileDialogResult.None and the dialog settings are only stored.
- Cloud: No dialog can be shown in the cloud: ShowDialog returns FileDialogResult.None and the dialog settings are only stored.

C#:

```csharp
public string DefaultExt {get; set;}
```

Python:

```python
openFileDialog.DefaultExt: str
```

### Returns

`string` — 

Available since cAlgo.API 5.1.

### Examples

C#:

```csharp
var openFileDialog = new OpenFileDialog { DefaultExt = "txt", Filter = "Text files (*.txt)|*.txt" };
openFileDialog.ShowDialog();
Print("Default extension: {0}", openFileDialog.DefaultExt);
```

Python:

```python
openFileDialog = OpenFileDialog()
openFileDialog.DefaultExt = "txt"
openFileDialog.Filter = "Text files (*.txt)|*.txt"
openFileDialog.ShowDialog()
api.Print(f"Default extension: {openFileDialog.DefaultExt}")
```