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
# declaring the string str = "Geeks for Geeks !"# accessing the character of str at 0th index print(str[0]) # accessing the character of str at 6th index print(str[6]) # accessing the character of str at 10th index print(str[10]) |
G f G
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
# declaring the string str = "Geeks for Geeks !"# accessing the character of str at last index print(str[-1]) # accessing the character of str at 5th index from the last print(str[-5]) # accessing the character of str at 10th index from the last print(str[-10]) |
! e o
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
# declaring the string str ="Geeks for Geeks !"# slicing using indexing sequence print(str[: 3]) print(str[1 : 5 : 2]) print(str[-1 : -12 : -2]) |
Gee ek !seGrf
Example 2 :
python3
# declaring the string str ="Geeks for Geeks !"print("Original String :-") print(str) # reversing the string using slicing print("Reverse String :-") print(str[: : -1]) |
Original String :- Geeks for Geeks ! Reverse String :- ! skeeG rof skeeG
