Fundamental of Python : 2.Python Strings

Fundamentals of Python

---

2. Python Strings

Python strings are sequences of characters enclosed within either single (') or double (") quotation marks. Strings are immutable, which means once created, their contents cannot be changed. They are widely used for storing and manipulating text data. Python provides numerous operations and methods to work efficiently with strings.

Python also allows dynamic typing, so the type is automatically inferred at runtime when values are assigned.

Key operations include:

1. Concatenation: Combining multiple strings.
2. Length Calculation: Determining the number of characters.
3. Type Conversion: Converting strings to integers and vice versa.
4. Formatting: Embedding variables or values within strings.
5. Case Manipulation: Converting to upper or lower case.
6. Substring Access: Extracting portions of the string using indexing and slicing.
7. Trimming: Removing specified leading and trailing characters using string methods.

Let’s explore string operations with examples:

🔹 1. String Creation

Program:

'hello' is the same as "hello".

You can display a string literal with the print() function:

#Create string

>>>s="Hello World!"

>>>type(s)

Result : <type ’str’>

Explanation: The variable s is assigned a string. Python recognizes it as a string type.

🔹 2. String Concatenation

Program:

#String concatenation
>>>t="This is sample program."
>>>r = s+t
>>>r

Result : 'Hello World!This is sample program.

Explanation: Using the + operator joins two strings. No automatic space is inserted between them.

🔹 3. Length of a String

Program:

#Get length of string
>>>len(s) 

Result : 12

Explanation: len() returns the number of characters, including spaces and punctuation.

🔹 4. String to Integer Conversion

Program:

#Convert string to integer
>>>x="100"
>>>type(s)
result : <type ’str’>
>>>y=int(x)
>>>y 
Result : 100

Explanation: The string "100" is successfully converted to an integer using int().

🔹 5. Printing a String

Program:

#Print string

>>>print s 

Result : Hello World!

Explanation: The print() function displays the string to the output screen.

🔹 6. Formatting Output

Program:

#Formatting output
>>>print 

Result : "The string (The string (Hello World!) has 12 characters)

Explanation: The format() method dynamically inserts values into a string template.

🔹 7. Case Conversion

Program:

#Convert to upper/lower case
>>>s.upper()
Result : 'HELLO WORLD!’
>>>s.lower()

Result : 'hello world!’ 

Explanation: upper() converts all characters to uppercase; lower() converts them to lowercase.

🔹 8. Accessing Substrings

Program:

#Accessing sub-strings
>>>s[0]
Result : 'H’
>>>s[6:]
Result : 'World!’
>>>s[6:-1]
Result : 'World’

Explanation:
s[0] accesses the first character.
s[6:] extracts from the 7th character to the end.
s[6:-1] retrieves a slice excluding the last character.

🔹 9. Trimming Characters

Program:

#strip: Returns a copy of the string with the #leading and trailing characters removed.
>>>s.strip("!")
Result : 'Hello World’

Explanation: The strip() method removes the specified characters from both ends of the string—in this case, the exclamation mark.

---

🔸 Summary:

Python strings are powerful tools for managing and processing text. From accessing specific characters to formatting and transforming data, strings offer a wide range of functionalities crucial in every Python application.

📢 If you found this post helpful, don’t forget to share it with your fellow learners, follow for more Python tips, and drop a comment below with your thoughts or questions! 🐍💬