Back to: Python Programming
What is String?
String is a sequence of characters surrounded by single or double quotations, where character is a letter in alphabet, a digit, a special symbol like punctuation mark, a space, a tab, etc.
String example:
'Hello World!' or
"Hello World!"
You can simply print a string like :
print('Hello World')
print("Hello World")
Output:
Hello World
Hello World
Assigning String to a variable:
strg = "This is a string"
print(type(strg))
print(strg)
Output:
<class 'str'>
This is a string
Note: In Python there is no character type like in Java or C#. So, if define
strg = ‘a’
then strg is also a string.
String Operations:
Determining the length of a String: A string’s length is the number of character available in that string. There are many built-in function in Python language, one of them is len(), which is used to determine the length of the String. Ex:
strg = 'Hello World'
print(len(strg))
Output: 11
String in Python is an array of characters. Simply array is a data structure which contains same type of data in the contiguous memory locations. Positions of the characters in the array start from 0. We can use Square brackets [ ] to access the characters/elements of the string. We will see array in detail in the latter chapters.
Let’s see an example :
strg = "This is a string"
print(strg[0])
print(strg[0:4])
print(strg[1:4])
length = len(strg)
print(strg[length-1])
print(strg[0:length])
Output:
T
This
his
g
This is a string
In the above example, we saw how we can get part of the string or sub-string.
Different built-in function for string processing in Python:
Function | Description | Example |
len() | Returns the length of the string. | strg = “This is a String, it lovely!” length = len(strg) print(length) Output: 31 |
lower() | Converts all the characters of the string to lowercase characters | strg = “This is a String, it is lovely!” lower_strg = strg.lower() print(lower_strg) Output: this is a string, it is lovely! |
upper() | Converts all the characters of the string to uppercase characters | strg = “This is a String, it is lovely!” upper_strg = strg.upper() print( upper_strg ) Output: THIS IS A STRING, IT IS LOVELY! |
replace() | Can replace whole or part of the string with another string | strg = “This is a String, it is lovely!” print(strg.replace(‘lovely’, ‘not lovely’)) print(strg.replace(‘, it is lovely!’, ‘ ‘)) Output: This is a String, it is not lovely!This is a String |
strip() | Removes whitespace from the beginning and the end of the string | strg = ” This is a String, it is lovely! “ print(strg.strip()) Output: This is a String, it is lovely! |
split() | Splits the string to make smaller or substrings according to the separator and returns an array of the substrings | strg = ” This is a String, it is lovely! “ splitted_str_array = strg.split(‘,’) print(splitted_str_array) print(splitted_str_array[0]) Output: [‘ This is a String’, ‘ it is lovely! ‘] This is a String |