Python Type Conversion Complete Guide

# Example 1: int to float
num_int = 10      # integer
num_float = 3.14  # float

# Python automatically converts int to float
result = num_int + num_float
print(result)              # 13.14
print(type(result))        # 

# Example 2: int to float in division
a = 5
b = 2
result = a / b            # Division always returns float
print(result)             # 2.5
print(type(result))       # 

# Example 3: bool to int in arithmetic
is_true = True    # bool (True = 1, False = 0)
is_false = False
num = 10

result1 = num + is_true   # 10 + 1 = 11
result2 = num + is_false  # 10 + 0 = 10
print(f"10 + True = {result1}")   # 11
print(f"10 + False = {result2}")  # 10

# Example 4: Complex number operations
x = 5           # int
y = 3 + 2j      # complex

result = x + y  # int converted to complex
print(result)   # (8+2j)
print(type(result))  # 

# These will cause ValueError
# int("hello")      # Cannot convert text to number
# int("3.14")       # String with decimal point
# float("abc")      # Not a valid number
# int("")           # Empty string
# int("123abc")     # Contains letters

# These will cause TypeError
# int([1, 2, 3])    # Cannot convert list to int
# float((1, 2, 3))  # Cannot convert tuple to float
# list(100)         # Integer is not iterable

def safe_convert(value, target_type):
    """Safely convert value to target type"""
    try:
        if target_type == int:
            return int(value)
        elif target_type == float:
            return float(value)
        elif target_type == str:
            return str(value)
        elif target_type == bool:
            return bool(value)
        elif target_type == list:
            return list(value)
        elif target_type == tuple:
            return tuple(value)
        else:
            raise ValueError(f"Unsupported target type: {target_type}")
    except (ValueError, TypeError) as e:
        print(f"Conversion error: {e}")
        return None  # Or raise exception based on your needs

# Usage examples
print(safe_convert("100", int))      # 100
print(safe_convert("hello", int))    # None (prints error)
print(safe_convert("3.14", float))   # 3.14
print(safe_convert([1, 2, 3], tuple)) # (1, 2, 3)

def get_integer_input(prompt):
    """Get integer input from user with validation"""
    while True:
        user_input = input(prompt)
        try:
            # Try to convert to integer
            number = int(user_input)
            return number
        except ValueError:
            print(f"Error: '{user_input}' is not a valid integer. Please try again.")

def get_float_input(prompt):
    """Get float input from user with validation"""
    while True:
        user_input = input(prompt)
        try:
            # Try to convert to float
            number = float(user_input)
            return number
        except ValueError:
            print(f"Error: '{user_input}' is not a valid number. Please try again.")

# Usage
age = get_integer_input("Enter your age: ")
print(f"You entered age: {age}")

price = get_float_input("Enter price: ")
print(f"Price entered: ${price:.2f}")

# Simple calculator with type conversion
print("Simple Calculator")
print("Enter two numbers")

# Get input (always returns string)
num1_str = input("Enter first number: ")
num2_str = input("Enter second number: ")

# Convert strings to floats
try:
    num1 = float(num1_str)
    num2 = float(num2_str)
    
    # Perform calculations
    print(f"\nResults:")
    print(f"{num1} + {num2} = {num1 + num2}")
    print(f"{num1} - {num2} = {num1 - num2}")
    print(f"{num1} × {num2} = {num1 * num2}")
    
    # Handle division by zero
    if num2 != 0:
        print(f"{num1} ÷ {num2} = {num1 / num2}")
    else:
        print(f"{num1} ÷ {num2} = Cannot divide by zero")
        
except ValueError:
    print("Error: Please enter valid numbers!")

# Processing user data with type conversion
def process_user_data(data_list):
    """Process list of user data strings"""
    processed_data = []
    
    for item in data_list:
        try:
            # Try to convert to appropriate type
            if item.isdigit():  # Check if it's an integer
                processed_data.append(int(item))
            elif '.' in item and item.replace('.', '', 1).isdigit():
                # Check if it's a float (one decimal point)
                processed_data.append(float(item))
            elif item.lower() in ['true', 'false']:
                # Convert string boolean to actual boolean
                processed_data.append(item.lower() == 'true')
            else:
                # Keep as string
                processed_data.append(item.strip())
        except:
            # If conversion fails, keep original
            processed_data.append(item)
    
    return processed_data

# Sample data (from CSV file or user input)
raw_data = ["25", "19.99", "True", "John", "42.5", "False", "100"]
processed = process_user_data(raw_data)

print("Original data:", raw_data)
print("Processed data:", processed)
print("\nTypes after processing:")
for item in processed:
    print(f"{item} → {type(item).__name__}")

# Useful type conversion utility functions

def to_number(value, default=0):
    """Convert any value to number if possible"""
    try:
        # Try int first
        return int(value)
    except ValueError:
        try:
            # Try float if int fails
            return float(value)
        except (ValueError, TypeError):
            return default

def string_to_list(string, delimiter=','):
    """Convert delimited string to list"""
    if not string:
        return []
    return [item.strip() for item in string.split(delimiter)]

def list_to_dict(pairs):
    """Convert list of (key, value) pairs to dictionary"""
    try:
        return dict(pairs)
    except (ValueError, TypeError):
        return {}

# Usage examples
print(to_number("100"))        # 100
print(to_number("3.14"))       # 3.14
print(to_number("abc", 999))   # 999 (default)

csv_data = "apple,banana,cherry"
print(string_to_list(csv_data))  # ['apple', 'banana', 'cherry']

key_value_pairs = [("name", "John"), ("age", 30)]
print(list_to_dict(key_value_pairs))  # {'name': 'John', 'age': 30}