1. If Statements (Basic Conditionals)

The if statement is the fundamental way to execute code conditionally. The code inside the if block runs only if the condition evaluates to True.

 language = "python"
 if language == "python":
  print("Language is Python") # This will be executed
 
 if True:
  print("This will always print")
 
 if False:
  print("This will never print")
 

2. Boolean Values and Comparisons

Boolean values are True or False. Conditional statements rely on expressions that evaluate to a Boolean value.

Common comparison operators:

• == (equal to)
• != (not equal to)
• > (greater than)
• < (less than)
• >= (greater than or equal to)
• <= (less than or equal to)
• is (object identity)

 x = 5
 y = 10
 
 print(x == y)  # Output: False
 print(x != y)  # Output: True
 print(x < y)  # Output: True
 

3. Else Statements

The else statement provides an alternative block of code to execute when the if condition is False.

 language = "java"
 if language == "python":
  print("Language is Python")
 else:
  print("No match")  # Output: No match
 

4. Elif Statements (Else If)

elif (else if) allows you to check multiple conditions in sequence.

 language = "java"
 if language == "python":
  print("Language is Python")
 elif language == "java":
  print("Language is Java") # Output: Language is Java
 else:
  print("No match")
 

5. Boolean Operations (And, Or, Not)

Boolean operators combine or modify conditions.

• and: Both conditions must be True.
• or: At least one condition must be True.
• not: Negates a condition.

 user = "admin"
 logged_in = True
 
 if user == "admin" and logged_in:
  print("Admin page") # Output: Admin page
 
 if user == "admin" or logged_in:
  print("Admin page or logged in") # Output: Admin page or logged in
 
 if not logged_in:
  print("Please log in")
 

6. Object Identity (is Keyword)

== checks for equality of values, while is checks if two variables refer to the same object in memory.

 a = [1, 2, 3]
 b = [1, 2, 3]
 
 print(a == b)  # Output: True (same values)
 print(a is b)  # Output: False (different objects)
 
 b = a
 print(a is b)  # Output: True (same object)
 
 print(id(a))
 print(id(b))
 
 
 
 
 

7. Truthiness and Falsiness in Python

Certain values implicitly evaluate to False:

• False
• None
• Zero of any numeric type (0, 0.0)
• Empty sequences ("", [], ())
• Empty mappings ({})

Everything else generally evaluates to True.

 condition = ""
 if condition:
  print("Evaluated to True")
 else:
  print("Evaluated to False") # Output: Evaluated to False
 
 condition = "test"
 if condition:
  print("Evaluated to True") # Output: Evaluated to True
 else:
  print("Evaluated to False")