> ## 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 Do-While Loop
A `do-while` loop in Dart is a post-test control flow structure that guarantees the execution of its block of code at least once before evaluating a boolean condition to determine whether to continue iterating. Because the condition is evaluated at the end of the loop's lifecycle, the initial execution occurs unconditionally.
## Syntax
```dart theme={"dark"}
do {
// Statement(s) to execute
} while (condition);
```
## Execution Flow
1. **Execution:** The statement(s) inside the `do` block are executed immediately.
2. **Evaluation:** The `condition` expression is evaluated.
3. **Branching:**
* If the `condition` evaluates to `true`, control flow returns to the beginning of the `do` block.
* If the `condition` evaluates to `false`, the loop terminates, and control flow proceeds to the next statement in the program.
## Code Example
```dart theme={"dark"}
int counter = 0;
do {
print('Iteration: $counter');
counter++;
} while (counter < 3);
```
**Output:**
```text theme={"dark"}
Iteration: 0
Iteration: 1
Iteration: 2
```
## Technical Characteristics
* **Strict Boolean Evaluation:** Dart enforces strict type safety. The `condition` expression must evaluate to a literal `bool` type. Dart does not support "truthy" or "falsy" type coercion (e.g., `while (1)` will result in a compile-time error).
* **State Mutation:** To prevent infinite loops, the block of code within the `do` statement must eventually mutate the state evaluated in the `while` condition, or utilize a control transfer statement like `break`.
* **Scope:** Variables declared inside the `do` block are block-scoped and cannot be accessed within the `while` condition. Variables evaluated in the condition must be declared in an outer scope prior to the loop.
```dart theme={"dark"}
// Invalid Scope Example
do {
int x = 5;
} while (x > 0); // Error: 'x' is undefined in this scope.
// Valid Scope Example
int y = 5;
do {
y--;
} while (y > 0); // Valid: 'y' is declared in the outer scope and mutates to terminate.
```
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