Page 225 - Robotics and AI class 10
P. 225
Output:
enter a name Susan
Hello Susan Happy Learning
Accessing the Elements of the String
Each character in a string has a unique address called an index. The index number is always an integer which can
be negative, zero or positive. A single character in a string can be accessed using an index number enclosed in
square brackets([ ])
There are two different ways of using the index number:
• Forward Indexing: The index number begins with 0 till length-1 and we refer the elements from left to right.
• Negative/Backward Indexing: The index number begins with -1 till-length and we refer to the elements from
right to left. Negative indices are used when we want to access the characters of the string from right to left.
Example:
>>> S1="PYTHON"
Forward Indexing 0 1 2 3 4 5
P Y T H O N
–6 –5 –4 –3 –2 –1 Backward Indexing
Each element can be accessed by using:
stringname[index number]
print(S1[0]) P
print(S1[3]) H
print(S1[-3]) H
print(S1[-1]) N
print(S1) #print complete string PYTHON
print(S1[0],S1[4]) P O
print(S1[1+4]) N
print(S1[10] ) IndexError: string index out of range
print(S1[5.5]) TypeError: string indices must be integers
String is Immutable
Strings in Python are immutable. It means that the content of the string cannot be changed after it is created.
For example:
>>> s3 = "WELCOME"
>>> s3[2]="!"
TypeError: 's3' object does not support item assignment
Introduction to Data and Programming with Python 223

