Python Strings Indexing and Slicing

stringname[Start: End: Step]

G	I	R	I	S	H
0	1	2	3	4	5
-6	-5	-4	-3	-2	-1

Strings can be indexed, with the first character having index 0

>>> mystr = "GIRISH"
>>> mystr
'GIRISH'
>>> mystr[0]  # character in position 0
'G'
>>> mystr[1]  # character in position 1
'I'
>>> mystr[5]  # character in position 5
'H'
>>> mystr[6]  # Out of range Index will throw IndexError
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: string index out of range

Negative Indexing start from -1

>>> mystr[-1]  # last character
'H'
>>> mystr[-6]  # first character of the given string (refer above for negative indexing)
'G'
>>> mystr[-7]  # Out of range Index will throw IndexError
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: string index out of range

Indexing is used to obtain individual characters, slicing allows you to obtain substring. Start is always included, and the end always excluded. s[:i] + s[i:] is always equal to s, where s is a string.

>>> mystr[0:2]  # characters from position 0 (included) to 2 (excluded)
'GI'
>>> mystr[2:5]  # characters from position 2 (included) to 5 (excluded)
'RIS'

Slice indices have useful defaults; an omitted first index defaults to zero, an omitted second index defaults to the size of the string being sliced.

>>> mystr[:2]  # character from the beginning to position 2 (excluded)
'GI'
>>> mystr[4:]  # characters from position 4 (included) to the end
'SH'
>>> mystr[-2:]  # characters from the second-last (included) to the end
'SH'
>>> mystr[:-2]  # going up to but not including the last 2 chars.
'GIRI'

>>> mystr[1:44] # out of range slice indexes are automatically handled
'IRISH'
>>> mystr[44:]
''

>>> mystr[::2] # step value is 2
'GRS'
>>> mystr[::-2]
'HII'
>>> mystr[:]
'GIRISH'
>>> mystr[::-1] # String Reverse
'HSIRIG'

References

• https://docs.python.org/3/tutorial/introduction.html

Learn more about Python features in our upcoming blog articles.

Happy Learning!