Strings in Python

We generally use strings in python to do operations characters. Strings are immutable objects that mean we cannot delete or update a string once it is declared or assigned to a variables.

String is type of immutable data type of python. String is defined either in double code "Cleo" or in single 'Cleo'. Creating strings is as simple as assigning a value to a variable.

Accessing string elements (String Slicing)

#Defining string

str = 'Goeduhub Technologies 12345'

print('str = ', str)

#first character

print('str[0] = ', str[0])

#last character

print('str[-1] = ', str[-1])

#slicing 1nd to 5th character

print('str[1:5] = ', str[1:5])

#slicing 5th to 2nd last character

print('str[5:-2] = ', str[5:-2])

#space cosider as string element

print('str[8]=',str[8])

Output

str = Goeduhub Technologies 12345 str[0] = G str[-1] = 5 str[1:5] = oedu str[5:-2] = hub Technologies 123 str[8]=

Note: As you can see from the above output string is a heterogeneous type of data type.

Indexing of a String

Indexing of string is similar to list

Note: From left to right is started from 0 to n, and from right to left it started from -1 to -n.

n- here n is last element of the string

Basic Operation on String str1 = 'Python'

str2 ='String'

concatenating strings

print('str1 + str2 = ', str1 + str2)

printing string multiple time

print('str1 2 =', str1 2)

Output

str1 + str2 = PythonString

str1 * 2 = PythonPython

DELETING AND UPDATING A STRING Str1 = "Python Programming"

print(Str1)

Updating a element of string

Str1[2] = 'a'

print(Str1)

Output

Note: As we know string is immutable means we can't update/ delete a element of string. If we try it, it will give us a error as shown in above output.So, conclusion is if you want to delete an element of a string you have to delete entire string.

So, basically creating a new string is the solution of this problem, see the example below

Str1 = "Python Programming"

Deleting a element of string

del Str1

Creating new string

Str1= "Creating new string"

print(Str1)

Output

Creating new string

String Formatting

Default order

Str1 = "{} {} ".format('python', 'programming')

print(Str1)

Positional Formatting

Str2= "{1} {0} ".format('python','programming')

print(Str2)

Keyword Formatting

Str1 = "{g} {t} {j}".format(g = 'Goeduhub', t= 'Technologies', j = 'Jaipur')

print(Str1)

Output

python programming programming python Goeduhub Technologies Jaipur

String Function and Methods Python has number of functions and methods but here you can see some important function and methods, see the table below

Function/ Method Description string.lowercase A string must contain lowercase letters. string.uppercase A string must contain uppercase letters. String.index Returns the position of the first occurrence of substring in a string replace() returns a copy of the string where all occurrences of a substring is replaced with another substring. String.Isalnum Returns true if all the characters in a given string are alphanumeric. String.len Returns the length of the string. String.Max Returns the highest alphabetical character in a string. string.capitalize Return a word with its first character capitalized. string.split Return a list of the words of the string,If the optional second argument sep is absent or None string.strip() It return a copy of the string with both leading and trailing characters removed We can also access string elements using loop

count = 0

for letter in 'Goeduhubuu':

if(letter == 'u'):

    count += 1

print(count,' times u letter found in given string')

Output

4 times u letter found in given string

How to use function/ Method in string

str1= "Goeduhub Python programming"

print(len(str1),"Length of given string")