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Constants

In Python, constants are not explicitly defined, but we rely on a naming convention to indicate that a variable should be treated as a constant, meaning its value should not be changed throughout the program. Typically, constant variable names are written in uppercase characters.

Example 1: Pi as a Constant​

# Define pi as a constant
PI = 3.1415

# Using pi in calculations
radius = 2
area = PI * radius**2

# Display the calculated area
print(f"The area of a circle with radius {radius} is: {area}")

Example 2: Version Number as a Constant​

# Define the version number as a constant
VERSION = 2

# Display the program version
print(f"This is version {VERSION} of the program.")

Important Points​

  • Constants in Python are not enforced, and the naming convention is used to indicate their immutability.
  • While constants are conventionally not changed, Python does not prevent you from modifying them.
  • Follow best practices and avoid modifying constant values to maintain the integrity of your program.