How to return to previous part of the program (Python)
I’m novice in python and got a problem in which I would appreciate some help. The problem in short:
- ask for a string
- check if all letter in a predefined list
- if any letter is not in the list then ask for a new string, otherwise go to next step
- ask for a second string
- check again whether the second string’s letters in the list
- if any letter is not in the list then start over with asking for a new FIRST string
basicly my main question is how to go back to a previous part of my program, and it would also help if someone would write me the base of this code. It start like this:
4 Answers 4
You have a couple of options, you could use iteration, or recursion. For this kind of problem I would go with iteration. If you don’t know what iteration and recursion are, and how they work in Python then you should use the links Kugel suggested.
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В Python можно отменить последние действия, используя конструкцию undo . Например, если вы случайно удалили строки кода, вы можете вернуть их обратно, воспользовавшись этой функцией.
Чтобы использовать undo , вы должны вызвать метод undo() объекта, к которому хотите его применить. Этот метод можно вызвать несколько раз, чтобы отменить несколько последних операций.
some_code = «. «some_code = some_code[:-1] # Удаление последнего символаsome_code = some_code[:-1] # Удаление еще одного символаsome_code = some_code[:-1] # Удаление третьего символаsome_code.undo() # Отмена удаления третьего символаsome_code.undo() # Отмена удаления еще одного символа
Этот код удаляет последние 3 символа строки some_code, а затем отменяет последние 2 действия, вернув строку к исходному состоянию.
Важно понимать, что undo работает только для объектов, которые поддерживают эту функцию. Некоторые встроенные типы, такие как числа и кортежи, не поддерживают undo . Если попытаться вызвать этот метод для объекта, который не поддерживает эту функцию, возникнет ошибка.
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