in his ancient laboratory, the alchemist Alister found an amazing potion. If you drop it on a parchment with a number, the potion begins to hiss and glow, and then a magic symbol appears in the air, meaning the number of numbers in this number. Alister, being not only an alchemist, but also an enthusiast of a new “technomagic” (programming), decided to recreate this effect with the code.
rnyour task & mdash; Help the alister and write a program-prison. This spell should take one number to the input and determine how many numbers are in it.
rnimportant magic rules:
rn& nbsp;
One is an entire number that the alchemist supplies to the input of his device (an integer/integer).
The number of digits in the input number (integral number / Integer).
-481516
6
In the Python programming language, the while loop construction can have an optional else block. This block is executed only when the loop completes in its natural way, that is, when its condition becomes false, and not as a result of a forced interruption using the break operator.
Syntax:
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while condition:
# the body of the loop
# ...the code that runs on each iteration...
else:
# else block
# ...the code that is executed if the loop ended without a break...
You can think of the else block as a "plan B": it is triggered if the main goal within the loop (which is usually completed through a break) has not been achieved.
Consider a classic problem where we search for a number in a list. If a number is found, we immediately break the loop using break. If we have checked all the elements and still haven't found what we are looking for, the else block is executed.
numbers = [1, 2, 3, 4, 5]
target = 8 # Let's try to find a number that is not in the list.
index = 0
while index < len(numbers):
if numbers[index] == target:
print(f"Success! {target} found at {index}.")
break # Goal reached, exit the loop
index += 1
else:
# This block will be executed because break was not called
print(f"The search is completed. {target} not found in the list.")
How it works:
whileloop is executed as long as the index < len(numbers) condition is true.target).break statement. The else block is ignored in this case.break has never worked. The index < len(numbers) condition becomes false, and then the else block is executed, reporting a failed search.A useful tip: Using while...else helps to avoid "flagged" variables. Without this block, the code would look like this:
# Alternative version with "flag"
numbers = [1, 2, 3, 4, 5]
target = 8
found = False # Flag variable
index = 0
while index < len(numbers):
if numbers[index] == target:
found = True
break
index += 1
if found:
print(f"Success! {target} found.")
else:
print(f"Search completed. {target} not found in the list.")
As you can see, the while...else construction makes the code cleaner, more concise, and more "Pythonic", eliminating the need to manually control the flag.
break is missingIf there is no break operator in the body of the while loop, then the else block will always be executed after the loop ends.
count = 0
while count < 3:
print(f"Iteration number {count}")
count += 1
else:
print("The loop ended naturally, so the else block is executed.")
Here, the while loop runs until count is less than 3. As soon as count becomes 3, the loop condition becomes false, and control is transferred to the else block.
continue? The continue operator does not interrupt the loop, but only ends the current iteration ahead of schedule. It does not affect the execution of the else block in any way.while condition is initially false, the loop body will not be executed even once. However, the else block will still run, since the loop ended "normally" (it was not interrupted via break).value = 10
while value < 5: # The condition is immediately false
print("This text will never be printed")
else:
print("The cycle didn't even start, but it ended normally, so else worked.")
for loops! The same logic applies to for...else loops. The else block after for is executed if the cycle has passed through all the elements and has not been interrupted using break.The while...else construction is a powerful and elegant Python tool. It is ideal for situations where you need to perform an action only if the loop has completed its work completely without being interrupted. This is especially useful in search algorithms, condition checking, or when working with data streams, where break signals a special event, and else indicates a regular termination without any.
# Считываем входные данные от пользователя в виде строки
input_str = input()
# Преобразуем строку в целое число
number = int(input_str)
# Инициализируем счетчик цифр
digit_count = 0
# Проверяем особый случай: если число равно 0
if number == 0:
# В числе 0 ровно одна цифра
digit_count = 1
else:
# Если число отрицательное, делаем его положительным для удобства подсчета
if number < 0:
number = -number # Знак минуса не является цифрой
# Запускаем цикл, который будет работать, пока в числе есть цифры
while number > 0:
# Целочисленно делим число на 10, отбрасывая последнюю цифру
number = number // 10
# Увеличиваем счетчик на 1 за каждую отброшенную цифру
digit_count = digit_count + 1
# Выводим итоговое количество цифр
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