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I have a string n = "abc".
I want to reverse it and found a solution like n[::-1].
What is the meaning of all 3 arguments?
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Python also allows you to index from the end of the list using a negative number, where [-1] returns the last element. This is super-useful since it means you don't have to programmatically find out the length of the iterable in order to work with elements at the end of it.
The new line character in Python is \n . It is used to indicate the end of a line of text.
In Python strings, the backslash "\" is a special character, also called the "escape" character. It is used in representing certain whitespace characters: "\t" is a tab, "\n" is a newline, and "\r" is a carriage return. Conversely, prefixing a special character with "\" turns it into an ordinary character.
it is binary "and". Eg 7 = 111 111 and 001 = 1 Actually it is a test if a number i is odd. if yes, the result is 1.
It means, "start at the end; count down to the beginning, stepping backwards one step at a time."
The slice notation has three parts: start, stop, step:
>>> 'abcdefghijklm'[2:10:3] # start at 2, go upto 10, count by 3
'cfi'
>>> 'abcdefghijklm'[10:2:-1] # start at 10, go downto 2, count down by 1
'kjihgfed'
If the start and stop aren't specified, it means to go through the entire sequence:
>>> 'abcdefghijklm'[::3] # beginning to end, counting by 3
'adgjm'
>>> 'abcdefghijklm'[::-3] # end to beginning, counting down by 3
'mjgda'
This is explained nicely in Understanding slice notation, in the Python docs under "extended slicing", and in this blogpost: Python Slice Examples: Start, Stop and Step
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