📜 Strings in Python
📖 String Basics
Strings are a fundamental data type in Python used to handle text. They can be created using single, double, or triple quotes, which can span multiple lines.
🔎 String Operations
Escape Characters in Strings
Escape sequences are used to include special characters in strings:
[BASH]# Include a new line character
print(“First Line\nSecond Line”)
# Include a tab character
print(“Column1\tColumn2”)
# Include a backslash character
print(“This is a backslash: \\”)[/BASH]
String Concatenation and Indexing
Strings can be concatenated and indexed to extract specific parts:
[BASH]# Concatenation
first_name = “John”
last_name = “Doe”
full_name = first_name + ” ” + last_name
print(full_name) # Output: John Doe
# Indexing and Slicing
phrase = “Python Programming”
print(phrase[7:18]) # Output: Programming
print(phrase[:6]) # Output: Python
print(phrase[-11:]) # Output: Programming
[/BASH]
String Immutability
Since strings are immutable, any modification creates a new string:
[BASH]original = “immutable”
modified = original.replace(“immutable”, “mutable”)
print(modified) # Output: mutable
[/BASH]
🧩 String Methods
Common String Methods
[BASH]# Using .find() to locate a substring
text = “Hello, Python!”
position = text.find(“Python”)
print(position) # Output: 7
# Using .replace() to replace a substring
new_text = text.replace(“Python”, “World”)
print(new_text) # Output: Hello, World!
# Using .strip() to remove leading and trailing whitespace
whitespace_str = ” Hello, World! “
print(whitespace_str.strip()) # Output: Hello, World!
[/BASH]
String Formatting
String formatting allows for embedding variables into strings:
[BASH]# Using .format() for string formatting
name = “Alice”
age = 30
formatted_str = “Name: {}, Age: {}”.format(name, age)
print(formatted_str) # Output: Name: Alice, Age: 30
# Using f-strings for string formatting (Python 3.6+)
formatted_str_f = f”Name: {name}, Age: {age}”
print(formatted_str_f) # Output: Name: Alice, Age: 30
[/BASH]
✍️ Exercises: String Manipulation
1- Print a string with a newline character:
[BASH]
print(“Line 1\nLine 2\nLine 3”)
[/BASH]
2- Print a string with a tab character:
[BASH]
print(“Name\tAge”)
print(“Alice\t30”)
[/BASH]
3- Replace characters in a string:
[BASH]
sentence = “I love Python.”
new_sentence = sentence.replace(“Python”, “programming”)
print(new_sentence) # Output: I love programming.
[/BASH]
4- Find and replace a substring in a string:
[BASH]
quote = “To be or not to be, that is the question.”
updated_quote = quote.replace(“be”, “exist”)
print(updated_quote) # Output: To exist or not to exist, that is the question.
[/BASH]
🔢 Numbers in Python
📖 Numeric Types
Python supports different numeric types, including integers and floats. You can also use scientific notation for large numbers.
[BASH]
# Integer
integer_value = 1_000_000
print(integer_value) # Output: 1000000
# Float with exponential notation
float_value = 1.75e5
print(float_value) # Output: 175000.0
[/BASH]
Integer and Float Types
Basic Arithmetic Operations
Perform various arithmetic operations using Python:
[BASH]
# Arithmetic operations
a = 15
b = 4
print(a + b) # Output: 19
print(a – b) # Output: 11
print(a * b) # Output: 60
print(a / b) # Output: 3.75
# Zero Division Error Handling
try:
result = a / 0
except ZeroDivisionError:
print(“Cannot divide by zero!”)
# Rounding Numbers
number = 2.675
print(round(number, 2)) # Output: 2.68
# Floor Division and Modulus
print(a // b) # Output: 3
print(a % b) # Output: 3
[/BASH]
🧩 Advanced Numeric Operations
Exponentiation
[BASH]
# Exponentiation
base = 2
exponent = 3
result = base ** exponent
print(result) # Output: 8
[/BASH]
Use Functions
[BASH]
#Using round(), abs(), pow(), and .is_integer()
number = -5.432
print(round(number, 2)) # Output: -5.43
print(abs(number)) # Output: 5.432
print(pow(2, 3)) # Output: 8
print(3.0.is_integer()) # Output: True
print(3.1.is_integer()) # Output: False
[/BASH]
✍️ Exercises: Numeric Operations
1- Calculate the area of a circle:
[BASH]
import math
radius = float(input(“Enter the radius of the circle: “))
area = math.pi * (radius ** 2)
print(f”The area of the circle is: {area:.2f}”)
[/BASH]
2- Convert a float to an integer and vice versa:
[BASH]
float_num = 123.456
int_num = int(float_num)
print(f”Float: {float_num}, Integer: {int_num}”)
int_num = 789
float_num = float(int_num)
print(f”Integer: {int_num}, Float: {float_num}”)
[/BASH]
3- Calculate the product of two numbers provided by the user:
[BASH]
num1 = float(input(“Enter the first number: “))
num2 = float(input(“Enter the second number: “))
product = num1 * num2
print(f”The product of {num1} and {num2} is {product}.”)
[/BASH]
4- Format a number as currency and percentage:
[BASH]
amount = 1000
percentage = 0.85
# Currency formatting
print(f”${amount:,.2f}”)
# Percentage formatting
print(f”{percentage:.0%}”)
[/BASH]
✍️ Exercises: Numeric Operations
1- Calculate the area of a circle:
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