Definition
- In Python, a string is a sequence of characters enclosed within single (‘ ‘), double (” “), or triple quotes (”’ ”’ or “”” “””).
- Strings are immutable, i.e. they cannot be changed after creation.
- Strings in Python are powerful and come with many built-in methods for manipulation.
String Creation/Declaration
- We can define strings using:-
str1 = ‘Hello India’ # Using Single quotes
str2 = “Hello India” # Using Double quotes
str3 = “1234”
str4 = “Hello 242”
str5 = ”’For Multiline String”’ # Triple quotes (Applicable for multi-line strings)
print(str1, str2, str3,str4,str5)
print()
print(str1)
print(str2)
print(str3)
print(str4)
print(str5)
Output:
Hello India Hello India 1234 Hello 242 For Multiline String
Hello India
Hello India
1234
Hello 242
For Multiline String
Accessing Characters in a String
- Strings in Python are indexed and support slicing features.
- For example –
s = “Python”
print(s[0])
print(s[-1])
print(s[1:4])
print(s)
print(s[0:-1])
print(s[0:5])
print(s[0:6])
Output:
P
n
yth
Python
Pytho
Pytho
Python
String Operations
- Python provides several operations on strings:-
a) Concatenation (+)
s1 = “Hello”
s2 = “India”
print(s1 + ” “ + s2) # Output: Hello India
b) Repetition (*)
print(“Hello “ * 3) # Output: Hello Hello Hello
c) Membership (in, not in)
Built-in String Methods
- Python provides many methods to manipulate strings, but some common are:-
| Methods | Descriptions | Examples |
len() |
Find the length of the String | s = "Hello"
print(len(s)) # Output: 5 |
lower() |
Converts to lowercase | "Hello".lower() → "hello" |
upper() |
Converts to uppercase | "hello".upper() → "HELLO" |
strip() |
Removes whitespace | " Hello ".strip() → "Hello" |
replace(old, new) |
Replaces substring | "Hello".replace("H", "J") → "Jello" |
split(delim) |
Splits string into list | "Hello World".split() → ["Hello", "World"] |
join(iterable) |
Joins elements of iterable | "-".join(["Hello", "World"]) → "Hello-World" |
find(sub) |
Finds index of substring | "Python".find("th") → 2 |
String Formatting
Python provides multiple ways to format strings:
a) Using format()
b) Using f-strings (In Python 3.6+)
c) Using % formatting (Old method)
Escape Sequences
- Escape sequences are special characters used in strings to format the strings in the desired way:
| Escape Sequence | Description | Example |
\n |
Newline | "Hello\nWorld" |
\t |
Tab space | "Hello\tWorld" |
\' |
Single quote | 'It\'s Python' |
\" |
Double quote | "She said \"Hello\"" |
\\ |
Backslash | "C:\\Users\\Name" |
String Immutability
- Since strings are immutable in Python, i.e. they cannot be changed after creation directly.
But, to modify a string indirectly, we must do it in a new way: –
Looping in a String
- We can iterate through a string using a loop as below:-
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