Python Input & Output Notes

Python Input & Output Notes

Objectives

• Understanding Variables & Data Types

• Converting Between Data Types

• Input and Output Operations:

• Using the print function

• Using the input function

• Print Hello World as a first exercise:

• Code:
  python print("Hello World!")

Variables & Data Types

• Variables: Containers for storing data values.

• Use meaningful names (e.g., first_name, last_name, age) instead of generic names (e.g., a, b, c).

Common Data Types

• String (str): Sequence of characters.

• Example:
  python first_name = "John"

• Integer (int): Whole numbers.

• Example:
  python age = 20

• Float: Decimal numbers.

• Example:
  python interest_rate = 5.2

• Boolean (bool): Values of True or False.

• Example:
  python scan_completed = True

Checking Data Types

• Use type(...) to check the data type of a variable:

• Example:
  python print(type(first_name))
  Returns:

Important Rules

• Variable Naming Convention:

• Use lowercase with underscores for normal variables.

• Use uppercase with underscores for constants.

Input Handling

• Getting Input from the User:

• Use input() to prompt users for information.

• Example:
  python first_name = input("Enter your first name: ") last_name = input("Enter your last name: ") full_name = first_name + " " + last_name print("My name is " + full_name + ".")

• Converting Input to Desired Data Type:

• Input is taken as a string by default. To convert it:

  • For integers:
    python number = int(input("Enter an integer: "))

  • For floats:
    python decimal_number = float(input("Enter a decimal number: "))

Converting Between Data Types

• Common Conversions:

• To convert strings to integers: int(variable)

• To convert strings to floats: float(variable)

• To convert numbers to strings: str(variable)

• Python does not allow concatenating strings and numbers directly. Convert numbers to strings first.

Output Formatting

• Use the print() function effectively, including features like end to control line endings.

• Example:
  python print("Hello", end=" ") print("World")

• String Addition (Concatenation):
  python full_name = "John" + " " + "Smith"

• Output: My name is John Smith.

Comments

• Use comments generously to explain code.

• Comments can be added anywhere in the program for clarity.

• Always write comments before the related code.

Python Keywords

• Important keywords to remember include: if, else, elif, for, while, def, import, print, etc.

Conclusion

• Always follow best practices with naming conventions, data types, and code structure to write clean and maintainable Python code.