(i) The format( ) function used with strings is very versatile and powerful function used for formatting strings.
(ii) The curly braces {} are used as placeholders or replacement fields which get replaced along with format( ) function.
Example:
num1 = int (input("Number 1:")) 
num2 = int (input("Number 2:")) 
print ("The, sum of {} and {} is {}". format (num1, num2, (num1 + num2)))
Output:
Number 1: 34
Number 2: 54
The sum of 34 and 54 is 88.

Output:
Weool

Str 1 = "COMPUTER"
index = 0
for i in str 1:
print (str 1[:index -1])
index =1

str1=input ("Enter a string:")
str2="aAeEiloOuU"
v,c=0,0
for i in str1:
if i in str2:
v+=1
else:
c+=1
print ("The given string contains {} vowels and {} consonants".format(v.c))
Output:
Enter a string: Tamilnadu School Education.
The given string contains 11 vowels and 15 consonants.

strl=' * '
i=1
while i< = 5:
print (strl*i)
i+=1

str1 = input ("Enter a string:")
str2 ="
index=-1
for i in str1:
str2 += str1[index]
index -=1
print ("'The given string = {} \n The Reversed string = {}".format(str1, str2))
if (str1==str2):
print ("Hence, the given string is Palindrome")
else:
print ("Hence, the given is not a palindrome")
Output:1
Enter a string: malayalam
The given string = malayalam
The Reversed string = malayalam
Hence, the given string is Palindrome
Output: 2
Enter a string: welcome
The given string = welcome
The Reversed string = emoclew
Hence, the given string is not a palindrome

String Operators:
Python provides the following operators for string operations. These operators are useful to manipulate string.
(i) Concatenation (+):
Joining of two or more strings is called as Concatenation. The plus (+) operator is used to concatenate strings in python.
Example:
>>> "welcome" + "Python"
'welcome python'
(ii) Append (+ =):
Adding more strings at the end of an existing string is known as append. The operator += is used to append a new string with an existing string.
Example:
>>> str1 = "welcome to"
>>> str1 + = "Learn Python"
>>> print (str1)
Welcome to Learn Python
(iii) Repeating (*):
The multiplication operator (*) is used to display a string in multiple number of times.
Example:
>>> str1= "welcome "
>>> print (str1 *4)
Welcome Welcome Welcome Welcome
(iv) String slicing:
Slice is a substring of a main string.
A substring can be taken from the original string by using [ ] operator and index or subscript values. Thus [ ] is also known as slicing operator. Using slice operator, we have to slice one or more substrings from a main string.
General format of slice operation:
str[start:end]
Where start is the beginning index and end is the last index value of a character in the string. Python takes the end value less than one from the actual index specified.
Example: I
Slice a single character from a string
>>>str 1 = "THIRUKKURAL"
>>>print (str 1 [0])
       T
(v) Stride when slicing string:

• When the slicing operator, we can specify a third argument as the stride, which refers to the number of characters to move forward after the first character is retrieved from the string.
• The default  value of stride is 1
• Python takes the last value as n-1
• We can also use negative value stride, to print data in reverse order.

Example :
>>>str1 = "Welcome to learn python"
>>>print(str1[::-2])
Output :
nhy re teolW