Control flow statements

• if and else

• for loops

• while and do-while loops

• break and continue

• switch and case

• assert

if / else

if (isRaining()) {
  you.bringRainCoat();
} else if (isSnowing()) {
  you.wearJacket();
} else {
  car.putTopDown();
}

for / for .. in ..

var message = StringBuffer('Dart is fun');
for (var i = 0; i < 5; i++) {
  message.write('!');
}

var callbacks = [];
for (var i = 0; i < 2; i++) {
  callbacks.add(() => print(i));
}
callbacks.forEach((c) => c());

for (final candidate in candidates) {
  candidate.interview();
}

while / do .. while

while (!isDone()) {
  doSomething();
}

do {
  printLine();
} while (!atEndOfPage());

switch .. case

var command = 'OPEN';
switch (command) {
  case 'OPEN':
    executeOpen();
    break;
  default:
    executeUnknown();
}

var command = 'CLOSED';
switch (command) {
  case 'CLOSED': // Empty case falls through.
  case 'NOW_CLOSED':
    // Runs for both CLOSED and NOW_CLOSED.
    executeNowClosed();
    break;
}

var command = 'CLOSED';
switch (command) {
  case 'CLOSED':
    executeClosed();
    continue nowClosed;
  // Continues executing at the nowClosed label.

  nowClosed:
  case 'NOW_CLOSED':
    // Runs for both CLOSED and NOW_CLOSED.
    executeNowClosed();
    break;
}

assert

assert(urlString.startsWith('https'),
    'URL ($urlString) should start with "https".');