Page 363 - Computer Science V2.0 Class 11

str. Tests whether the string str ends >>>string_s1.endswith('ence')
endswith(subStr) with the suffix subStr, passed as a True
parameter.
str.find(subStr) Returns the index of the first >>>string_s1.find('e')
occurrence of the string passed as an 15
argument.
str.rfind(subStr) Returns the index of the last occurrence >>>string_s1.rfind('e')
of a substring in the given string. 23

str.index(subStr) Returns the index of the first >>>string_s1.index('en')
occurrence of the substring passed as 21
an argument.
str.replace(old, Returns a string where all occurrences >>> string_s1= 'Touchpad
new) of the string old are replaced by the Computer Science'
string new. >>> string_s1.replace('e','z')

Touchpad Computzr Scizncz
str.split(delimit) Returns a list of substrings, separated >>> string_s1= 'Touchpad
by the given delimiter, delimit. Computer Science'

>>> string_s1.split(' ')
['Touchpad', 'Computer',
'Science']
str. Splits the string into three parts: the >>> string_s1= 'Touchpad
partition(delimit) part of the string before the delimiter, Computer Science'
the delimiter itself, and the part of the >>> string_s1.partition(' ')
string after the delimiter.
('Touchpad', ' ', 'Computer
Science')
str.join(list) Joins the strings in the given list >>>'#'.join(['Touchpad',
(comma-separated sequence of values 'Computer', 'Science'])
provided within square brackets) Touchpad#Computer#Science
together using the string str as the
delimiter.

12.4 Case Study

In this section, we will develop a module named stringFns.py that enables us to perform the following operations
on strings:
1. Form a string comprising distinct characters in a string, replacing uppercase characters with corresponding
lowercase characters.
2. Compute the number of matching characters in a pair of strings.
3. Find whether a string is a substring of another string.
4. Construct a string by reversing the sequence of the characters in the original string.

12.4.1 Distinct Characters in a String Ignoring the Case
To form a string comprising the distinct characters in a string, let us develop a function distinct() that takes a
string str1 as the input parameter.
● On execution of line 8, a string may comprise a mix of upper and lowercase characters, we first construct a string of
lowercase characters.
● Line 9, we initialize the string of distinct characters (distinctChars) to an empty string.

Strings 349