Question

Write a Python statement that defines a named constant for a 10 percent discount.

Short answer

Answer: In Python, constants can be defined by using uppercase letters for the variable name. To define a named constant for a 10 percent discount, you can use the name DISCOUNT_10_PERCENT and assign it the value 0.10. The Python statement to define this constant would be: ```python DISCOUNT_10_PERCENT = 0.10 ```

Step-by-step solution

Decide on the constant's name and value

Choose a descriptive name for the constant to represent a 10 percent discount, for example, DISCOUNT_10_PERCENT. Determine the numerical value for a 10 percent discount which is 0.10 as a decimal.

Defining the constant in Python

Python doesn't have built-in support for named constants like some other programming languages. However, by convention, we can define a constant by using uppercase letters for the variable name. Define the constant, DISCOUNT_10_PERCENT, and assign it the value 0.10. The Python statement to define the named constant for a 10 percent discount would be: ```python DISCOUNT_10_PERCENT = 0.10 ``` This statement defines a constant named DISCOUNT_10_PERCENT and assigns it the value 0.10, representing a 10 percent discount.

Key concepts

Defining Constants in Python

In Python, constants are a convenient way to assign names to fixed values that do not change throughout the execution of a program. To define a constant in Python, you simply assign a value to a variable. Since Python doesn't have built-in support for constants, developers use naming conventions to indicate a variable should be treated as a constant.

For instance, if you want to define a constant for a 10 percent discount, you would assign a decimal value representing 10 percent (0.10) to a variable. Here’s how to do it:

DISCOUNT_10_PERCENT = 0.10

This piece of code creates a constant called DISCOUNT_10_PERCENT and assigns it the value of 0.10. It is essential to understand that this is a naming convention and the assigned value can still be changed; Python doesn't enforce the immutability of constants.

Python Naming Conventions

Python has a set of rules generally known as naming conventions, which provide programmers with guidelines on how to name variables, functions, modules, and other objects in Python. These conventions are not enforced by the Python interpreter but are widely followed by Python developers for code readability and maintainability.

The convention for defining constants is to use all uppercase letters with underscores separating words. For example, MAX_SIZE, MIN_VALUE, or DISCOUNT_10_PERCENT are constants that clearly indicate their purpose and immutability. Following these naming conventions helps other programmers (and future you) understand the code's intention quickly and signals which variables should not be changed once set.

Python Programming Basics

Python is a versatile and widely-used programming language known for its simplicity and readability. Getting to grips with the basics of Python programming involves understanding its syntax, data types, control flow, functions, and more.

Basic Python syntax is clear and easy to learn. For example, you assign values to variables without needing to declare their data type and use indentation instead of braces to denote blocks of code. Python data types include integers, floats, strings, lists, and dictionaries. Control flow statements like if, else, and elif allow for conditional execution of code blocks. Loops such as for and while enable repetitive execution of code with iterable data structures or based on a condition. Understanding these basics is an essential step in developing Python programming skills.