> ## 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.
# Swift Repeat-While Loop
The `repeat-while` loop in Swift is a post-test control flow statement that executes a block of code at least once before evaluating its termination condition. It is Swift's equivalent to the `do-while` loop found in C-based languages.
## Syntax
```swift theme={"dark"}
repeat {
// Statements to execute
} while condition
```
## Execution Flow
1. **Unconditional Execution:** The program enters the `repeat` block and executes the enclosed statements sequentially. This first pass happens regardless of the state of the condition.
2. **Condition Evaluation:** Upon reaching the `while` clause at the end of the block, the boolean `condition` is evaluated.
3. **Branching:**
* If the condition evaluates to `true`, control flow jumps back to the beginning of the `repeat` block for another iteration.
* If the condition evaluates to `false`, the loop terminates, and control flow proceeds to the next statement immediately following the loop structure.
## Code Example
```swift theme={"dark"}
var iterationCount = 0
repeat {
iterationCount += 1
print("Execution number: \(iterationCount)")
} while iterationCount < 3
```
## Technical Characteristics
* **Post-Condition Evaluation:** Because the condition is evaluated at the end of the loop rather than the beginning (pre-test), the loop body is structurally guaranteed a minimum of one execution.
* **Strict Boolean Requirement:** The expression provided to the `while` clause must evaluate explicitly to a `Bool` type (`true` or `false`). Swift's type safety prevents implicit type coercion; passing an integer (like `1` or `0`) or an optional will result in a compile-time error.
* **Variable Scope:** Variables declared inside the `repeat` block are scoped locally to that block and are not accessible within the `while` condition clause. To evaluate a variable in the `while` condition, it must be declared in the outer scope prior to the `repeat` keyword.
## Scope Example
```swift theme={"dark"}
// Correct Scope
var index = 0
repeat {
index += 1
} while index < 5
// Compilation Error (Unresolved Identifier)
repeat {
var localIndex = 0
localIndex += 1
} while localIndex < 5
```
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