Guidelines

A Container for Data, Variables

In programming, a Variable is essentially a container for storing data.

You can assign a name to data to store a value, and you can modify or reference the stored value as needed.


The Meaning of Variables

A variable is basically a name that points to a location in memory (an area used to temporarily store data and instructions) for storing data.

In Python, you don't need any special keywords (e.g., var, let) to declare a variable. Simply use a variable name and assign a value with the equals sign (=).

Variable Declaration and Assignment
my_variable = 10 # Assign 10 to the variable my_variable name = "CodeFriends" # Assign "CodeFriends" to the variable name

Declaring and Initializing Variables

To declare a variable means to prepare the variable for use.

When declaring a variable, assigning a value to it is referred to as initialization.

Declaring and Initializing a Variable
# Declare the variable my_var my_var = 10 # Initialize by assigning 10

In Python, if you declare a variable without initializing it, a NameError will occur.

Declaring a Variable without Initialization
# Attempt to declare a variable without initialization x # NameError: name 'x' is not defined

Therefore, when declaring a variable in Python, you must initialize it using the equals sign (=).


Characteristics of Python Variables

  • Dynamic Typing: The data type (the form of data like text or numbers) of a variable is determined during the program's execution, and there's no need to pre-declare the variable type.

  • Reassignable: You can change the value stored in a variable or reassign it with a value of a different type.

Dynamic Typing and Reassignment
number = 5 # Assign an integer (number) number = "five" # Reassign with a string (text)

Coding Exercise

Try assigning the string "hello" to the variable greeting.

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In Python, you have to use a var or let keyword to declare a variable.

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