Python Tutorial for Beginners 7 String (Tamil) Anna University

Python Strings: Replace, Join, Split, Reverse, Uppercase & Lowercase

In Python everything is object and string are an object too. Python string can be created simply by enclosing characters in the double quote.

For example:

var = "Hello World!"
In this tutorial, we will learn -

Accessing Values in Strings

Python does not support a character type, these are treated as strings of length one, also considered as substring.

We use square brackets for slicing along with the index or indices to obtain a substring.

var1 = "Tamiltechzone!"

var2 = "Software Testing"

print ("var1[0]:",var1[0])

print ("var2[1:5]:",var2[1:5])

Various String Operators

There are various string operators that can be used in different ways like concatenating different string.

Suppose if a=tamiltechzone and b=99 then a+b= "tamiltechzone". Similarly, if you are using a*2, it will "TamiltechzoneTamiltechzone". Likewise, you can use other operators in string.

Operator	Description	Example
[]	Slice- it gives the letter from the given index	a[1] will give "u" from the word Tamiltechzone as such ( 0=G, 1=u, 2=r and 3=u)	x="Tamiltechzone" print x[1]
[ : ]	Range slice-it gives the characters from the given range	x [1:3] it will give "ur" from the word Tamiltechzone. Remember it will not consider 0 which is G, it will consider word after that is ur.	x="Tamiltechzone" print x[1:3]
in	Membership-returns true if a letter exist in the given string	u is present in word Tamiltechzone and hence it will give 1 (True)	x="Tamiltechzone" print "u" in x
not in	Membership-returns true if a letter exist is not in the given string	l not present in word Tamiltechzone and hence it will give 1	x="Tamiltechzone" print "l" not in x
r/R	Raw string suppresses actual meaning of escape characters.	Print r'\n' prints \n and print R'/n' prints \n
% - Used for string format	%r - It insert the canonical string representation of the object (i.e., repr(o)) %s- It insert the presentation string representation of the object (i.e., str(o)) %d- it will format a number for display	The output of this code will be "tamiltechzone 99".	name = 'tamiltechzone' number = 99 print'%s %d' % (name,number)
+	It concatenates 2 strings	It concatenate strings and gives the result	x="Tamiltechzone" y="99" print x+y
*	Repeat	It prints the character twice.	x="Tamiltechzone" y="99" print x*2

Some more examples

You can update Python String by re-assigning a variable to another string. The new value can be related to previous value or to a completely different string all together.

x = "Hello World!"

print(x[:6])

print(x[0:6] + "Tamiltechzone")

Note : - Slice:6 or 0:6 has the same effect

Python String replace() Method

The method replace() returns a copy of the string in which the values of old string have been replaced with the new value.

oldstring = 'I like Tamiltechzone'

newstring = oldstring.replace('like', 'love')

print(newstring)

Changing upper and lower case strings

In Python, you can even change the string to upper case or lower case.

Likewise, you can also do for other function as well like capitalize

string="python at tamiltechzone"              

print(string.capitalize())

You can also convert your string to lower case

string="PYTHON AT TAMILTECHZONE""

print(string.lower())

Using "join" function for the string

The join function is a more flexible way for concatenating string. With join function, you can add any character into the string.

For example, if you want to add a colon (:) after every character in the string "Python" you can use the following code.

print(":".join("Python"))      

Reversing String

By using the reverse function, you can reverse the string. For example, if we have string "12345" and then if you apply the code for the reverse function as shown below.

string="12345"         

print(''.join(reversed(string)))

Split Strings

Split strings is another function that can be applied in Python let see for string "tamiltechzone career tamiltechzone". First here we will split the string by using the command word.split and get the result.

word="tamiltechzone career tamiltechzone"            

print(word.split(' '))

To understand this better we will see one more example of split, instead of space (' ') we will replace it with ('r') and it will split the string wherever 'r' is mentioned in the string

word="tamiltechzone career tamiltechzone"            

print(word.split('r'))

Important Note:

In Python, Strings are immutable.

Consider the following code

x = "Tamiltechzone"

x.replace("Tamiltechzone","Python")

print(x)

will still return Tamiltechzone. This is because x.replace("Tamiltechzone","Python") returns a copy of X with replacements made

You will need to use the following code to observe changes

x = "Tamiltechzone"

x = x.replace("Tamiltechzone","Python")

print(x)

Above codes are Python 3 examples, If you want to run in Python 2 please consider following code.

Python 2 Example

#Accessing Values in Strings

var1 = "Tamiltechzone!"

var2 = "Software Testing"

print "var1[0]:",var1[0]

print "var2[1:5]:",var2[1:5]

#Some more examples

x = "Hello World!"

print x[:6]

print x[0:6] + "Tamiltechzone"

#Python String replace() Method

oldstring = 'I like Tamiltechzone'

newstring = oldstring.replace('like', 'love')

print newstring

#Changing upper and lower case strings

string="python at tamiltechzone"

print string.upper()

string="python at tamiltechzone"             

print string.capitalize()

string="PYTHON AT TAMILTECHZONE"

print string.lower()

#Using "join" function for the string

print":".join("Python")              

#Reversing String

string="12345"        

print''.join(reversed(string))

#Split Strings

word="tamiltechzone career tamiltechzone"           

print word.split(' ')

word="tamiltechzone career tamiltechzone"           

print word.split('r')

x = "Tamiltechzone"

x.replace("Tamiltechzone","Python")

print x

x = "Tamiltechzone"

x = x.replace("Tamiltechzone","Python")

print x

Python has introduced a .format function which does way with using the cumbersome %d and so on for string formatting.