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What are Strings in Python?

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What are Strings?

A string in Python refers to letters, numbers, symbols, spaces, or even emojis that are arranged in a specific order.

We can use strings in Python to store multiple string-based information, such as names, messages, sentences, and file paths.

  • Python stores every string as immutable, which means once a string is created, you cannot directly change any of its characters.
  • In simple words, a string is text, and Python keeps it safe by not allowing you to change its characters directly.

Important Examples of Strings:

# Strings with single quotes
title = 'Learning Python Strings!'
print(title)

# Strings with double quotes
note = "Coding becomes easy when you practice daily."
print(note)

# Strings with triple quotes (multiline string)
details = """This is a short description.
It covers multiple lines.
Python allows this using triple quotes."""
print(details)

Meaning of the Examples

  • Single quotes are used to create short text values. For example, it shows a simple sentence stored inside single quotes.
  • Double quotes work exactly like single quotes, but it’s useful when your text includes apostrophes.
  • Triple quotes used to store large text blocks or multiline messages. This is perfect for documentation, long notes, or formatted output.

What are apostrophes in Python?

An apostrophe is a small punctuation mark used in English. Let’s see the example between single and double quotes representation.

  • Example (problem):
text = 'I don’t know'
  • Better:
text = "I don’t know"
  • So double quotes are used to avoid errors when your string contains ‘ inside it.

How Python String Concepts Are Used in a Real Project

Imagine you are building a Food Delivery Application like Zomato or Swiggy. Strings play an extremely role in almost every part of this system.

  • When a customer places an order, the backend must prepare a clear, readable summary message.
  • This all the data send to:
    • Customer’s phone
    • Delivery partner’s app
    • Restaurant panel
    • Admin dashboard
  • This entire summary is built using Python strings.

Step-by-Step Breakdown

  • First, storing all the data using strings.
  • Then creating a message so we join multiple pieces of text.
  • Developers use f-strings to format the order message professionally.
  • Finally using a Type Casting to convert numbers into strings.

1) Storing Customer & Food Data Using Strings

customer_name = "Riya Sharma"
item = "Margherita Pizza"
address = "45 Sunrise Apartments, Mumbai"

2) String Concatenation: Creating a Message

msg = "Order for " + customer_name + " has been received."
  • We join multiple pieces of text to build a sentence.

3) String Formatting: Cleaner Summary Message

amount = 299.50

summary = f"""
Order Summary:
Customer: {customer_name}
Item: {item}
Total Amount: ₹{amount}
Delivery Address: {address}
"""

print(summary)
  • Developers use f-strings to format the order message professionally.
  • This looks exactly like a real company message.

4) Type Casting: Converting Numbers to Strings

price = 250
tax = 18
final = price + tax

message = "Payable Amount: " + str(final)
  • Here, prices, taxes, and discounts are numbers, so we converted them into strings to display.

5) String Slicing: Hiding Sensitive Data

phone = "9876543210"
masked = phone[:2] + "******" + phone[-2:]
print(masked)   # Output: 98******10
  • Then the app masks part of the phone number to protect privacy.

6) Multi-line Strings: Sending Long Messages

restaurant_msg = """
New Online Order Received!

Please prepare the food quickly.
Delivery partner will arrive at the pickup location soon.
"""
  • Restaurants receive detailed order messages using triple quotes:

7) String Methods: Cleaning User Input

raw = "   EXTra cheese please   "
cleaned = raw.strip().lower()
  • You already knows sometimes user contains extra spaces or mixed casing.
  • So, this method ensures the message is readable and uniform.

String Indexing and Slicing

A string is refers to a individual characters placed one after another. Python gives each character a numbered position (index), so we can easily access or extract specific parts of the string.

What Is String Indexing?

Indexing means selecting a single character from a string using its position number.

Python starts counting from:

  • 0 for the first character
  • 1 for the second
  • …
  • n−1 for the last

Python also supports negative indexing, which starts from the end:

  • -1 is the last character
  • -2 is the second last, and so on.

Example of Indexing:

word = "Sunrise"

print(word[1])   # Output: u (second character)
print(word[-3])  # Output: i (third character from the end)

What Is String Slicing?

String slicing means extracting a specific part of the string. For example:

phrase = "AdventureTime"

# Slice: characters from index 0 to 6 (excluding 6)
print(phrase[0:7])     # Output: Adventu

# Slice: from index 4 to the end
print(phrase[4:])      # Output: ntureTime

# Slice: from start to index 3
print(phrase[:4])      # Output: Adve

# Slice: every second character
print(phrase[::2])     # Output: AvnurTi

Meaning of phrase [0:0]

  • phrase [0:7] = Takes characters from index 0 up to 6 → Adventu
  • phrase [4:] = Starts at index 4 → continues till the end → ntureTime
  • phrase [:4] = Starts at the beginning → stops before index 4 → Adve
  • phrase [::2] = Takes every alternate character → AvnurTi

Essentials String Operations In Python

Python provides powerful operations that allow us to combine, repeat, or measure strings.

1. String Concatenation (Joining Strings)

  • Concatenation means joining two or more strings together to create a new string. Python uses the + operator to merge text smoothly.
  • This operation does not change the original strings because strings are immutable. For example:
first_name = "Riya"
last_name = "Sharma"

full_name = first_name + " - " + last_name
print(full_name)   

# Output: Riya - Sharma

2. String Repetition

  • Repetition means we can create a multiple copies of the same string. Python providing a * operator, which repeats the string as many times as the number you specify.
  • This operation is helpful when we are creating patterns, decorative output, or repeated messages.
pattern = "Hi! "
print(pattern * 4)   

# Output: Hi! Hi! Hi! Hi!

3. Finding String Length

  • The len() function tells you how many characters are present in a string, and this includes letters, numbers, spaces, and even hidden characters like \n.
  • This operation is especially useful in validation, formatting, and slicing operations.
message = "Learn Python Today"
print(len(message))   

# Output: 19

String Methods In Python

  • Python provides many built-in string methods that help you clean, modify, analyze, and transform text easily.
  • This method performs a specific task, so you don’t need to write long logic manually.

1. upper() and lower()

These methods convert all characters of a string into uppercase or lowercase.

  • upper() converts every letter to CAPITAL
  • lower() converts every letter to small
city = "MuMbAi"
print("Uppercase:", city.upper())     # Output: MUMBAI
print("Lowercase:", city.lower())     # Output: mumbai

2. strip()

  • It removes extra spaces at the beginning and the end of a string.
  • This method is useful for cleaning user input because people sometimes add extra spaces in inputs.
user_input = "   Learn Python   "
cleaned = user_input.strip()
print("Before:", repr(user_input))
print("After :", repr(cleaned))

3. replace()

  • This method replaces any specific part of the string with another value.
  • Perfect when you want to update a specific word inside a sentence
sentence = "Coding in Ruby is easy, but Ruby is not popular."
updated = sentence.replace("Ruby", "Python")
print(updated)

# Output: Coding in Python is easy, but Python is not popular.

4. split()

  • Breaks a string into smaller parts and returns a list.
  • It’s useful when we’re dealing with comma-separated or symbol-separated data.
data = "red#green#blue#yellow"
colors = data.split("#")
print(colors)

# Output: ['red', 'green', 'blue', 'yellow']

5. join()

  • This method joints list elements into a single string using a separator.
words = ["Code", "Create", "Build"]
sentence = " | ".join(words)
print(sentence)

# Output: Code | Create | Build

6. find()

  • When you search for a small piece of text (a substring) inside a bigger text (a string), Python will tell you the position where that small text begins.
text = "Welcome to the Python Universe"
position = text.find("Python")
print("Index:", position)
  • Output of this program:
Index: 11
  • here, “Python” begins at position 11 so our output will be 11.

7. isnumeric() and isalpha()

  • Checks what type of characters are available inside the string.
  • isnumeric() → True if the string contains only digits
  • isalpha() → True if the string contains only letters
value1 = "98245"
value2 = "Learning"

print(value1.isnumeric())   # True
print(value2.isalpha())     # True

Escape Characters

An escape character is a special symbol that is used to insert characters into a string. It always begins with a backslash (\).

These helps us to include:

  • Quotes inside quotes
  • New lines
  • Tabs
  • Special symbols
  • Characters with special meaning

Example of Escape Characters:

1) Using double quotes inside a double-quoted string

dialogue = "Teacher said, \"Always keep learning Python!\""
print(dialogue)

Output:

Teacher said, "Always keep learning Python!"

2) Using single quotes inside a single-quoted string

weather = 'Today\'s forecast says it\'ll rain in the evening.'
print(weather)

Output: 

Today's forecast says it'll rain in the evening.

More Escape Characters

1) New line (\n): It adds a line break inside a string

message = "Day 1: Learn basics\nDay 2: Practice coding"
print(message)

Output: 

Day 1: Learn basics
Day 2: Practice coding

2) ab space (\t): Adds a horizontal tab space

menu = "Item\tPrice\nCake\t₹120"
print(menu)

Output:

Item    Price
Cake    ₹120

3) Backslash (\\): Prints a single backslash.

path = "C:\\NewFolder\\Images"
print(path)

Output:

C:\NewFolder\Images

What Is String Formatting In Python?

String formatting insert a variables, values, or expressions into as string in a clean way. It means, replace a variables and added its value inside a sentence.

We can use two important methods:

1. f-strings (Recommended):

  • f-strings provide a easy way to insert variables directly inside curly braces {}. They start with the letter f before the string.
student = "Riya"
marks = 88
subject = "Maths"

message = f"{student} scored {marks} marks in {subject}."
print(message)

Output:

Riya scored 88 marks in Maths.

If we remove the f from the sentences, it will look like this:

student = "Riya"
marks = 88

message = "{student} scored {marks} marks."    # Print without f
print(message)

Output will be:

{student} scored {marks} marks.
  • It means Python does not replace the variables.

2. format() Method:

The format() method is another way to insert variables inside a string. Let’s see the example:

city = "Surat"
temperature = 32

report = "The temperature in {} is currently {}°C.".format(city, temperature)
print(report)

Output of the code:

The temperature in Surat is currently 32°C.

Immutable Nature of Strings

Strings are immutable, meaning we can’t change, replace, or edit their characters directly.

Example: Trying to Modify a String Directly

name = "Rocky"
name[2] = "d"    # Trying to replace 'c' with 'd'

Output: 

TypeError: 'str' object does not support item assignment
  • This error message means, we cannot edit characters inside a string because the string is read-only.

Exercise For Learners:

Task: Take a string and print the character that appears in the middle of the string. If the string length is even, print the two middle characters.

Example Input:

"Python"

Expected Output:

th

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