Python Basics: Printing Variables and Understanding Output Differences 🖨️

📋 Printing Multiple Variables

In Python, you can print multiple variables using a single print() statement. This simplifies the display of values:

c = "Shivank"
a = "Agarwal"
print(c, a)  # Output: Shivank Agarwal

Python automatically separates the values with a space, enhancing readability.

---

🔍 Difference Between print(c, a) and c, a

• Using print(c, a): Displays values directly without additional formatting:

  c = "Alex"
  a = "Doyle"
  print(c, a)  # Output: Alex Doyle

• Using c, a directly (in interactive environments like Jupyter Notebook or Colab): Displays the variables as a tuple:

  c, a  # Output: ('Alex', 'AgarDoyleal')

The key takeaway: print() is for formatted output, while just writing c, a shows the tuple representation.

---

🛠️ Why Use Variables?

Variables act as placeholders for data, simplifying your code by avoiding repetitive typing. For example:

# Instead of repeating values:
print(10 + 20)  
print(10 * 20)  

# Use variables:
x = 10
y = 20
print(x + y)  # Output: 30
print(x * y)  # Output: 200

This approach improves code clarity and reusability.

---

🔤 Variable Naming Rules

Follow these guidelines to name variables effectively:

✅ Allowed Characters:

1. Letters (a-z, A-Z)

2. Digits (0-9) – but cannot start with a digit.

3. Underscores (_)

❌ Not Allowed:

1. Special characters like @, #, -, $, etc.

2. Starting variable names with a digit.

🖍️ Examples:

Valid:

name = "Alice"
age = 30
_score = 95
total2 = 100

Invalid:

2total = 100  # Starts with a digit
first-name = "Bob"  # Contains a hyphen
@age = 25  # Contains special character

🧠 Case Sensitivity:

Variable names are case-sensitive:

age = 25
Age = 30
print(age)  # Output: 25
print(Age)  # Output: 30

✍️ Readable Names:

Use meaningful names for clarity:

first_name = "John"
last_name = "Doe"

---

🔄 Assigning Multiple Variables

You can assign the same value to multiple variables:

a = b = c = 10
print(a, b, c)  # Output: 10 10 10

---

⌨️ Taking User Input with input()

Interactive programs often use the input() function. Here’s how:

🔹 Basic Input:

name = input()
print(name)

The program waits for user input, which is then stored in the variable name.

🔹 Input with a Prompt:

name = input("Enter your name: ")
print("Hello", name)

Output:

Enter your name: Alice
Hello Alice

🔹 Important Note on Data Types:

Input values are always strings, even if the user enters numbers:

age = input("Enter your age: ")
print(type(age))  # Output: <class 'str'>

🔹 Converting Input to Numbers:

To work with numbers, explicitly convert the input:

age = int(input("Enter your age: "))
print(type(age))  # Output: <class 'int'>

For decimal numbers, use float().

---

📝 Common Printing Mistakes

• Enclosing a variable name in quotes prints it as a string:

  name = "Alice"
  print("name")  # Output: name
  print(name)    # Output: Alice

---

🧩 Example: Putting It All Together

# Asking for user input
first_name = input("Enter your first name: ")
last_name = input("Enter your last name: ")

# Concatenating strings
full_name = first_name + " " + last_name

# Displaying the result
print("Hello,", full_name)

Output:

Enter your first name: Shivank
Enter your last name: Agarwal
Hello, Shivank Agarwal

---

🔑 Recap of Key Points

• Printing Multiple Variables: Use print(var1, var2) for clear output.

• Variable Naming Rules:

  • Use letters, digits, and underscores.

  • Avoid starting with digits or using special characters.

  • Variable names are case-sensitive.

• Taking User Input:

  • Use input() for interaction.

  • Convert input to int or float when needed.

• Avoid Printing Mistakes: Ensure variables aren’t enclosed in quotes unless you intend to print their names.

---

🚀 Next Steps

In the next section, we’ll explore operators and expressions, delving into Python’s powerful tools for performing calculations, comparisons, and logical operations. Stay tuned! 😊