How do I get a substring of a string in Python?

Question

Is there a way to substring a string in Python, to get a new string from the third character to the end of the string?

Maybe like myString[2:end]?

Answer 1

Is there a way to substring a string in Python, to get a new string from the 3rd character to the end of the string?

Maybe like myString[2:end]?

Yes, this actually works if you assign, or bind, the name,end, to constant singleton, None:

>>> end = None
>>> myString = '1234567890'
>>> myString[2:end]
'34567890'

Slice notation has 3 important arguments:

• start
• stop
• step

Their defaults when not given are None - but we can pass them explicitly:

>>> stop = step = None
>>> start = 2
>>> myString[start:stop:step]
'34567890'

If leaving the second part means 'till the end', if you leave the first part, does it start from the start?

Yes, for example:

>>> start = None
>>> stop = 2
>>> myString[start:stop:step]
'12'

Note that we include start in the slice, but we only go up to, and not including, stop.

When step is None, by default the slice uses 1 for the step. If you step with a negative integer, Python is smart enough to go from the end to the beginning.

>>> myString[::-1]
'0987654321'

I explain slice notation in great detail in my answer to Explain slice notation Question.