• The reverse string in python is not an in-built function.
• By creating the slice operation we can perform the reverse function.
• In this slice operation, we create the slice that starts with the end of the string and moves backward.
• String reverse in python example program

                     gfedcba

 right to left indexing:              [-7]    [-6]    [-5]    [-4]      [-3]     [-2]      [-1]

                                                    a          b      c        d          e          f         g 

left to right indexing:             [0]         [1]     [2]     [3]     [4]       [5]        [6]

• In the above example, we are having the string  "abcdefg " which we want to reverse. so create a slice that starts with the end of the string and moves backward.
• here it starts with the end index that is indicated with -1 and moves backward as 5,4,3,2,1,0.
• -1 index  is g
• 5 index is f
• 4 index is e
• 3 index is d
• 2 index is c
• 1 index is b
• 0 index is a
• so the final output is gfedcba.

#write a python code to demonstrate string reverse.

1. txt="today climate is very cool"[::-1]
2. txt1="hello world"[::-1]
3. print(txt)
4. print(txt1)

Output:    looc yrev si etamilc yadot

                  dlrow olleh

•  In python, to lower is used to convert the uppercase letters to lower case.
• It uses the function called lower().
• It doesn't have any parameters.
• The string must be enclosed with single or double-quotes.
• If the string does not contain any upper case letters then it returns the same string.

Example: s="HELLO"

             str.lower(s)=hello

#write a python code to demonstrate the lower() function.

•  In python, we have different functions which remove the spaces between the strings.
• There are three functions that remove the whitespace between the strings, they are:
• strip(), rstrip(), lstrip()  are the three functions having the same meaning but some differences.

syntax: str.strip()

lstrip(): It removes the whitespace at beginning of the string.

syntax: str.rstrip()

rstrip(): It removes the whitespace at end of the string.

syntax: str.rstrip()

Example: write a python to demonstrate the remove space function.

1. txt="    hello"
2. print(txt)
3. print(txt.strip())
4. print(txt.rstrip())
5. print(txt.lstrip())

 replace function:

• The replace() function name itself saying that "one string is replaced with the other string".
• It consists of three parameters old value, new value, and count.

new value: The value we want to replace with is the new value.

count: The number of times of the value we want to replace old with the new value.

Syntax: str.replace(old value,new value,count)

#write a python code to demonstrate replace function.

• In python, we are having another in-built function called "strip()".
• The strip() function is used to remove the spaces of the starting and end of the string.
• It is having one parameter character used to remove the begging or end character.
• By default, it removes the white spaces at the beginning or end.
• If there is no white space between the beginning or end, the string remains the same and returns the same string.
• When the character we give does not match the start or end, it returns the same string.
• If the character is given at start to remove then the space will be removed and the remaining will remain the same.

#write a python program to demonstrate the strip function()

 length of the string:

• The len() function gives the length of the string.
• As it returns the result in integer type.
• It takes the string as the parameter.
• We can use len() for list,tuple,set,dictionry.
• The len() is the built-in function in python programming.
• Example:  "string"  its length is  6.

#write a python program to demonstrate the length of the string.