Booleans and Type Conversion

1. Boolean Values: True and False

Booleans are the foundation of decision-making in programming. You will use them extensively when you learn about if statements in a future module.

is_student = True
has_permission = False

print(is_student)
print(has_permission)
print(type(is_student))

Booleans often come from comparisons:

print(5 > 3)      # True (5 is greater than 3)
print(10 == 20)   # False (10 does not equal 20)
print(7 <= 7)     # True (7 is less than or equal to 7)
print("a" != "b") # True ("a" is not equal to "b")

2. Checking Types with type()

The type() function tells you what kind of data a value or variable holds:

print(type(42))          # <class 'int'>
print(type(3.14))        # <class 'float'>
print(type("hello"))     # <class 'str'>
print(type(True))        # <class 'bool'>
print(type(None))        # <class 'NoneType'>

value = "42"
print(type(value))  # <class 'str'> -- it's a string, not a number!
# value + 10 would cause a TypeError

3. Type Conversion Functions

Python provides built-in functions to convert between data types:

# String to number
age_text = "25"
age_number = int(age_text)
print(age_number + 5)  # Now we can do math!

# Number to string
price = 19.99
message = "The price is $" + str(price)
print(message)

# Integer to float and back
print(float(10))      # 10.0
print(int(9.7))       # 9 (truncates, does NOT round)

4. Common Conversion Errors

Not every conversion is possible. Python will raise an error if the conversion does not make sense:

# These will cause ValueError:
# int("hello")        # Cannot convert "hello" to a number
# int("3.14")         # Cannot convert "3.14" directly to int
# float("abc")        # Cannot convert "abc" to a float

# Solution for "3.14" to int: convert to float first, then to int
result = int(float("3.14"))
print(result)  # 3

# This is a very common mistake!
age = 25
# print("I am " + age + " years old")   # TypeError!

# The fix: convert age to a string
print("I am " + str(age) + " years old")

# Or even better, use an f-string (you'll learn this in Module 3!)
print(f"I am {age} years old")

5. Truthy and Falsy Values

Every value in Python can be treated as a Boolean. The bool() function shows you whether a value is considered "truthy" (converts to True) or "falsy" (converts to False).

# Falsy values
print(bool(0))       # False
print(bool(0.0))     # False
print(bool(""))      # False (empty string)
print(bool(None))    # False

# Truthy values
print(bool(42))      # True (any non-zero number)
print(bool(-1))      # True (negative numbers too!)
print(bool("hello")) # True (any non-empty string)
print(bool(" "))     # True (even a space is not empty!)

This concept becomes very useful when you start writing if statements. For now, just remember the pattern: zero and empty are False, everything else is True.

6. Putting It All Together

Let us look at a practical example that uses variables, different data types, and type conversion:

# A simple student info program
student_name = "Maria Garcia"
student_age = 19
gpa = 3.85
is_full_time = True

# Display info using type conversion
print("Student: " + student_name)
print("Age: " + str(student_age))
print("GPA: " + str(gpa))
print("Full-time: " + str(is_full_time))

# Check all the types
print("\nData types:")
print(type(student_name))
print(type(student_age))
print(type(gpa))
print(type(is_full_time))