> ## Documentation Index > Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt > Use this file to discover all available pages before exploring further. # Dart Await For Loop The `await for` loop is an asynchronous iteration construct in Dart used to consume events from a `Stream`. It suspends the execution of the enclosing `async` function until the stream emits a data event, executes the loop body with that event, and continues this process until the stream is closed. ## Syntax ```dart theme={"dark"} await for (variableDeclaration in streamExpression) { // Executes for each data event emitted by the stream } ``` ## Execution Mechanics To utilize an `await for` loop, the enclosing function must be marked with the `async` or `async*` modifier. The loop operates through the following lifecycle: 1. **Subscription:** The loop implicitly subscribes to the provided `Stream`. 2. **Suspension:** The execution of the enclosing function is suspended, yielding control back to the Dart event loop while waiting for the stream to emit an event. 3. **Execution:** When a data event is emitted, the variable is bound to the event data, and the loop body executes. 4. **Iteration:** Steps 2 and 3 repeat for every subsequent event. 5. **Termination:** The loop completes naturally, and execution proceeds to the next statement, only when the stream emits a "done" event indicating it is closed. ## Premature Termination and Cancellation You can interrupt an `await for` loop using standard control flow statements such as `break` or `return`. When the loop is exited prematurely, Dart automatically cancels the underlying stream subscription, preventing memory leaks and stopping further event generation if the stream is lazy. ## Error Handling If the stream emits an error event, the `await for` loop throws that error synchronously within the asynchronous context. The loop terminates immediately, and the subscription is canceled. These errors can be intercepted by wrapping the `await for` loop in a standard `try-catch` block. ## Code Example ```dart theme={"dark"} Stream generateStream() async* { yield 1; yield 2; // Stream closes automatically after the last yield } Future processStream() async { try { await for (final int event in generateStream()) { print(event); if (event == 2) { break; // Exits the loop and cancels the stream subscription } } } catch (e) { // Catches any error events emitted by the stream print('Caught stream error: $e'); } } ```

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