Swift While, Repeat and Loop Control

How it works

while checks before its body and repeat-while checks afterward. continue advances to the next iteration; break exits the current loop unless a label identifies another one. A manual counter must change on every path that is meant to make progress.

Run this Swift example

Install the toolchain for your platform from Swift.org, then check swift --version. The reviewed portable baseline is Swift 6.4.2 in Swift 6 mode on Ubuntu 26.04 x86_64 through the PC’s existing WSL installation. These are real Linux executions, not claims of Windows-native or Apple-platform test results. Windows Swift has separate C++/SDK prerequisites in its official setup guide.

Save the complete source as while-repeat-control.swift in a new learning folder. On Linux/macOS compile with swiftc -swift-version 6 -parse-as-library while-repeat-control.swift -o lesson, then run ./lesson. On a configured Windows toolchain use an output such as lesson.exe and run .\lesson.exe. The parse-as-library option supports the explicit @main entry point used by these sources. Compile each ordinary lesson separately.

Bhylu has no Swift browser runner. The JavaScript/Python editors do not run these sources; Apache, PHP and MySQL are not required. Downloads are source text, never executable teaching endpoints.

Download the complete while-repeat-control.swift · Download all source files with hash checks

For the optional collection, save download-examples.mjs in a new folder and run node download-examples.mjs. A local preview uses node download-examples.mjs http://127.0.0.1:8000/examples/swift/. It refuses an existing bhylu-swift-examples folder and installs or executes no Swift automatically. Apple-only files remain separate Xcode learning examples, not a portable Swift package target.

Example

@main
struct Lesson {
    static func main() {
        var remaining = 3
        while remaining > 0 {
            print(remaining)
            remaining -= 1
        }
        var attempts = 0
        repeat { attempts += 1 } while attempts < 1
        for number in 0...4 {
            if number == 0 { continue }
            if number == 3 { break }
            print("item", number)
        }
        print("attempts", attempts)
    }
}

Expected result

3
2
1
item 1
item 2
attempts 1

The repeat loop demonstrates the guaranteed first pass. The final loop skips zero and stops before three. A nested loop can use a label, but extracting a function often makes the exit easier to understand.