8.2. Loop While Patterns
Has stop conditions
>>> i = 0 >>> >>> while i < 3: ... print(i) ... i += 1 0 1 2
8.2.2. Infinite Loop
Never ending loop. Used in servers to wait forever for incoming connections. Used in games for game logic.
>>> ... while True: ... print('hello')
8.2.3. Exit Flag
>>> abort = False >>> i = 3 >>> >>> while not abort: ... print(i) ... i -= 1 ... ... if i == 1: # problem detected in the last second ... print('Fuel leak detected. Abort, Abort, Abort!') ... abort = True 3 2 Fuel leak detected. Abort, Abort, Abort!
In real life the exit flag pattern is useful if you have for example multi-threaded application. You can kill all the threads if any thread changes the flag. Multi-threaded apps will share this value and kill the loop as soon as the condition will be evaluated.