Saving Data to a Binary File - Python Programming Exercise

import struct

def save_data_to_binary(file_name):
    """
    Prompts the user for their name, age, and birth year, and saves this data into a binary file.
    
    Parameters:
    file_name (str): The name of the binary file to save the data.
    """
    # Get user input
    name = input("Enter your name: ")
    age = int(input("Enter your age (as a byte): "))
    birth_year = int(input("Enter your birth year: "))
    
    # Ensure the age is within byte range (0-255)
    if not (0 <= age <= 255):
        print("Age must be between 0 and 255.")
        return
    
    # Open the binary file in write mode
    with open(file_name, 'wb') as file:
        # Pack the data into a binary format
        # Name is encoded as a string, age as a byte (B), birth year as an integer (I)
        # '20s' ensures the name is stored as a string of up to 20 characters (padded with null bytes)
        data = struct.pack('20s B I', name.encode('utf-8'), age, birth_year)
        file.write(data)
    
    print(f"Data has been successfully written to {file_name}.")

def read_data_from_binary(file_name):
    """
    Reads the binary file and prints the saved data.
    
    Parameters:
    file_name (str): The name of the binary file to read the data from.
    """
    try:
        with open(file_name, 'rb') as file:
            # Read the binary data
            data = file.read()
            
            # Unpack the data: '20s B I' corresponds to a string (20 chars), a byte, and an integer
            name, age, birth_year = struct.unpack('20s B I', data)
            
            # Decode name from bytes and strip the null bytes
            name = name.decode('utf-8').rstrip('\x00')
            
            print(f"Name: {name}")
            print(f"Age: {age}")
            print(f"Birth Year: {birth_year}")
            
    except FileNotFoundError:
        print(f"The file '{file_name}' was not found.")
    except Exception as e:
        print(f"An error occurred: {e}")

# Main program execution
if __name__ == "__main__":
    file_name = 'user_data.bin'
    
    # Save the data to binary file
    save_data_to_binary(file_name)
    
    # Read and verify the saved data
    print("\nReading the saved data...\n")
    read_data_from_binary(file_name)

 Output

User Input:

Enter your name: John Doe
Enter your age (as a byte): 30
Enter your birth year: 1994

Program Output After Saving Data:

Data has been successfully written to user_data.bin.

Program Output After Reading Data:

Reading the saved data...
Name: John Doe
Age: 30
Birth Year: 1994