Page 351 - Computer Science V2.0 Class 11

12.1.4 Length of a String
To find the length of a string, Python provides a the built-in function len() which returns the length of a string. For
example,

>>> len('hello')
5
>>> len('hello\nhow are you')
17
>>> len('hello\n\n\nhow are you')
19
As the character sequence \n denotes a single end-of-line character, it is counted only once while computing the
length of the string.
12.1.5 Concatenation of Strings

The + operator is used to concatenate two strings. For example,
>>> 'Hello,' + 'How are you?' + 'I am good.' + 'How are you'
'Hello,How are you?I am good.How are you'
>>> 'Hello, ' + 'How are you? ' + 'I a good. ' + 'How are you'
'Hello, How are you? I am good. How are you'
12.1.6 Multiplication Operator
The multiplication operator (*) produces a string, concatenated with itself a specified number of times. For instance,
the expression 'Hello'*5 yields the string 'HelloHelloHelloHelloHello', i.e. the string 'Hello'
repeated five times (second operand:5). As expected, the expression 'Hello'*0 yields an empty string as the string
'Hello' is repeated zero times.

>>> 'Hello'*5
'HelloHelloHelloHelloHello'
>>> 'Hello'*0
''
The multiplication operator is quite useful when we want to print a pattern. For example, to print a 4-line pattern with
a single * in the first line, two *'s in the second line, three *'s in the third line, and finally, four *'s in the fourth line,
we simply invoke the print() function as follows:
>>> print('*' + '\n' + '*'*2 + '\n' + '*' * 3 + '\n' + '*' * 4)
*
**
***
****

len(): Returns the length of a string.
Operator +: Used to concatenate two strings.
Operator *: Concatenates a string with itself, a specified number of times.

12.1.7 Reverse of a String

Now we are ready to write a function reverse(str1) that generates a string having characters in the reversed sequence
of the original string; for example,

>>> reverse('excellent')
'tnellecxe'
>>> reverse('tnellecxe')
'excellent'

Strings 337