> ## Documentation Index
> Fetch the complete documentation index at: https://cdktn.io/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# CSharp: App
> CDKTN Core API Reference for App in CSharp.
Represents a cdktn application.
## Initializers
```csharp theme={null}
using Io.Cdktn;
new App(AppConfig Config = null);
```
| **Name** | **Type** | **Description** |
| ------------------------------------------------------------------------- | ----------------------------------------------------- | --------------- |
| Config | AppConfig | configuration. |
***
### `Config`Optional
* *Type:* AppConfig
configuration.
***
## Methods
| **Name** | **Description** |
| ----------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------- |
| ToString | Returns a string representation of this construct. |
| With | Applies one or more mixins to this construct. |
| CrossStackReference | Creates a reference from one stack to another, invoked on prepareStack since it creates extra resources. |
| Synth | Synthesizes all resources to the output directory. |
***
### `ToString`
```csharp theme={null}
private string ToString()
```
Returns a string representation of this construct.
### `With`
```csharp theme={null}
private IConstruct With(params IMixin[] Mixins)
```
Applies one or more mixins to this construct.
Mixins are applied in order. The list of constructs is captured at the
start of the call, so constructs added by a mixin will not be visited.
Use multiple `with()` calls if subsequent mixins should apply to added
constructs.
#### `Mixins`Required
* *Type:* params Constructs.IMixin\[]
The mixins to apply.
***
### `CrossStackReference`
```csharp theme={null}
private string CrossStackReference(TerraformStack FromStack, TerraformStack ToStack, string Identifier)
```
Creates a reference from one stack to another, invoked on prepareStack since it creates extra resources.
#### `FromStack`Required
* *Type:* TerraformStack
***
#### `ToStack`Required
* *Type:* TerraformStack
***
#### `Identifier`Required
* *Type:* string
***
### `Synth`
```csharp theme={null}
private void Synth()
```
Synthesizes all resources to the output directory.
## Static Functions
| **Name** | **Description** |
| ------------------------------------------------------------- | ----------------------------- |
| IsConstruct | Checks if `x` is a construct. |
| IsApp | *No description.* |
| Of | *No description.* |
***
### `IsConstruct`
```csharp theme={null}
using Io.Cdktn;
App.IsConstruct(object X);
```
Checks if `x` is a construct.
Use this method instead of `instanceof` to properly detect `Construct`
instances, even when the construct library is symlinked.
Explanation: in JavaScript, multiple copies of the `constructs` library on
disk are seen as independent, completely different libraries. As a
consequence, the class `Construct` in each copy of the `constructs` library
is seen as a different class, and an instance of one class will not test as
`instanceof` the other class. `npm install` will not create installations
like this, but users may manually symlink construct libraries together or
use a monorepo tool: in those cases, multiple copies of the `constructs`
library can be accidentally installed, and `instanceof` will behave
unpredictably. It is safest to avoid using `instanceof`, and using
this type-testing method instead.
#### `X`Required
* *Type:* object
Any object.
***
### `IsApp`
```csharp theme={null}
using Io.Cdktn;
App.IsApp(object X);
```
#### `X`Required
* *Type:* object
***
### `Of`
```csharp theme={null}
using Io.Cdktn;
App.Of(IConstruct Construct);
```
#### `Construct`Required
* *Type:* Constructs.IConstruct
***
## Properties
| **Name** | **Type** | **Description** |
| ------------------------------------------------------------------------------------------ | --------------------------------------------------- | --------------------------------------------------------------- |
| Node | Constructs.Node | The tree node. |
| HclOutput | bool | *No description.* |
| Manifest | Manifest | *No description.* |
| Outdir | string | The output directory into which resources will be synthesized. |
| SkipBackendValidation | bool | Whether to skip backend validation during synthesis of the app. |
| SkipValidation | bool | Whether to skip all validations during synthesis of the app. |
| TargetStackId | string | The stack which will be synthesized. |
***
### `Node`Required
```csharp theme={null}
public Node Node { get; }
```
* *Type:* Constructs.Node
The tree node.
***
### `HclOutput`Required
```csharp theme={null}
public bool HclOutput { get; }
```
* *Type:* bool
***
### `Manifest`Required
```csharp theme={null}
public Manifest Manifest { get; }
```
* *Type:* Manifest
***
### `Outdir`Required
```csharp theme={null}
public string Outdir { get; }
```
* *Type:* string
The output directory into which resources will be synthesized.
***
### `SkipBackendValidation`Required
```csharp theme={null}
public bool SkipBackendValidation { get; }
```
* *Type:* bool
Whether to skip backend validation during synthesis of the app.
***
### `SkipValidation`Required
```csharp theme={null}
public bool SkipValidation { get; }
```
* *Type:* bool
Whether to skip all validations during synthesis of the app.
***
### `TargetStackId`Optional
```csharp theme={null}
public string TargetStackId { get; }
```
* *Type:* string
The stack which will be synthesized.
If not set, all stacks will be synthesized.
***