How To Index and Slice Strings in Python?
Last Updated :
27 Apr, 2022
The Python string data type is a sequence made up of one or more individual characters that could consist of letters, numbers, whitespace characters, or symbols. As the string is a sequence, it can be accessed in the same ways that other sequence-based data types are, through indexing and slicing.
Indexing
Indexing means referring to an element of an iterable by its position within the iterable. Each of a string’s characters corresponds to an index number and each character can be accessed using its index number. We can access characters in a String in Two ways :
- Accessing Characters by Positive Index Number
- Accessing Characters by Negative Index Number
1. Accessing Characters by Positive Index Number: In this type of Indexing, we pass a Positive index(which we want to access) in square brackets. The index number starts from index number 0 (which denotes the first character of a string).
Indexing in Python
Example 1 (Positive Indexing) :
python3
str = "Geeks for Geeks !"
print ( str [ 0 ])
print ( str [ 6 ])
print ( str [ 10 ])
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2. Accessing Characters by Negative Index Number: In this type of Indexing, we pass the Negative index(which we want to access) in square brackets. Here the index number starts from index number -1 (which denotes the last character of a string). Example 2 (Negative Indexing) :
python3
str = "Geeks for Geeks !"
print ( str [ - 1 ])
print ( str [ - 5 ])
print ( str [ - 10 ])
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Slicing
Slicing in Python is a feature that enables accessing parts of the sequence. In slicing a string, we create a substring, which is essentially a string that exists within another string. We use slicing when we require a part of the string and not the complete string. Syntax :
string[start : end : step]
- start : We provide the starting index.
- end : We provide the end index(this is not included in substring).
- step : It is an optional argument that determines the increment between each index for slicing.
Example 1 :
python3
str = "Geeks for Geeks !"
print ( str [: 3 ])
print ( str [ 1 : 5 : 2 ])
print ( str [ - 1 : - 12 : - 2 ])
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Example 2 :
python3
str = "Geeks for Geeks !"
print ( "Original String :-" )
print ( str )
print ( "Reverse String :-" )
print ( str [: : - 1 ])
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Output
Original String :-
Geeks for Geeks !
Reverse String :-
! skeeG rof skeeG
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