Page 314 - Computer Science Class 11 With Functions
P. 314

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')


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