Page 262 - Computer Science Class 11 Without Functions
P. 262
C T 01
1. Write a program that accepts a string from the user and prints its reverse.
2. Rewrite the program mentioned in task 1 using negative indices.
11.2 Membership Operator in
We may examine the membership of a particular character or a substring in a given string using the membership
operator in. The expression <subStr> in <string1> returns True or False depending on whether the
string <subStr> is a substring of <string1>. For instance, in the following examples, 'h' is present in the string
'hello'; however, 'H' is not found in the string 'hello'.
>>> 'h' in 'Hello'
False
>>> 'h' in 'hello'
True
>>> 'ing' in 'playing'
True
The last expression returns True as the string 'ing' is the part of the string 'playing'.
Let us write a program that counts the number of digits in a string. For this purpose, we initialize the digit count
(digitCount) as zero and increment it by one every time a character of the input string belongs to the string
'0123456789'.
01 '''
02 Objective: To count the number of digits in a string.
03 Input: txt - string
04 Output: number of digits in string txt
05 '''
06
07 txt = 'Hello 123 hello 123'
08
09 digits = '0123456789'
10 digitCount = 0
11 for ch in txt:
12 if ch in digits:
13 digitCount +=1
14
15 print('No. of digits in \''+ txt + '\': ', digitCount)
Next, let us consider a more interesting piece of code:
01 s = 'abcdefghij' #Initial s
02 print('id(s):', id(s), 's:', s)
03 for ch in s:
04 s = s + ch
05 print('id(s):', id(s), 's:', s)
06 print('id(s):', id(s), 's:', s) # Final s
The above code yielded the following output on execution:
id(s): 1631127023152 s: abcdefghij
id(s): 1631126713008 s: abcdefghija
id(s): 1631126713008 s: abcdefghijab
id(s): 1631126713008 s: abcdefghijabc
id(s): 1631126713008 s: abcdefghijabcd
id(s): 1631126713008 s: abcdefghijabcde
id(s): 1631127097456 s: abcdefghijabcdef
id(s): 1631127097456 s: abcdefghijabcdefg
id(s): 1631127097456 s: abcdefghijabcdefgh
id(s): 1631127097456 s: abcdefghijabcdefghi
260 Touchpad Computer Science-XI

