Page 359 - Computer Science V2.0 Class 11

False
>>> ''.isspace()
False
Note that the function call ''.isspace() yields False because the empty string does not contain even a single
whitespace.

● s.startswith(subStr): The method startswith(subStr) tests whether the string s starts with the
string subStr, passed as a parameter. For instance, in the following example, the first and second function calls
returned True and False, respectively, as 'unethical' starts with 'un' and not with 'ethical'.

>>> 'unethical'.startswith('un')
True
>>> 'unethical'.startswith('ethical')
False
>>> 'hello'.startswith('')
True
Note that the function call 'hello'.startswith('') yields True, because the null string is a prefix of every
string and the expression '' + 'hello' yields 'hello'.
● s.endswith(subStr): The method endswith(subStr) tests whether the string s ends with the suffix
subStr, passed as an argument. For example,
>>> 'ethically'.endswith('ally')
True
>>> 'Bibasha Nayak'.endswith('Bibasha Nayak')
False
Note that in the function call 'Bibasha Nayak'.endswith('Bibasha Nayak') False, as the string
'Bibasha Nayak' contains an extra blank.
● s.find(subStr): The method find(subStr) searches for the first occurrence of the given string subStr in
the string s and returns the index of the first occurrence of the string passed as an argument. If the string subStr
does not appear anywhere in the string s, the method find() returns -1 indicating the condition substring not
found. For example,
>>> colors = 'green, red, blue, red, red, green'
>>> colors.find('red')
7
>>> colors.find('pink')
-1
While scanning the string colors from left to right, the string 'red' appears at indices 7, 18, and 23. So, invoking
colors.find('red') yields index 7, as the string 'red' appears first at index 7. However, since the substring pink
is not present in the string, named colors, the function call colors.find('pink') yields -1.
● s.rfind(subStr): The method rfind() returns the index of the last occurrence of a substring in the
given string. For example,

>>> colors = 'green, red, blue, red, red, green'
>>> colors.rfind('red')
23
● s.index(subStr): The method index(subStr) returns the index of the first occurrence of the substring
passed as an argument. But if the string specified as the argument is not found in the given string, Python raises
an exception. Thus, if the argument (subStr) is a substring of the given string (s), the methods find() and
index() yield the same result. For example,
>>> colors.find('blue')
12
>>> colors.index('blue')
12
>>> colors.find('pink')

Strings 345