The Difference between Local and Global Variables in Python
In Python, variables are an essential part of coding. Understanding the difference between local and global variables is crucial, as it affects the scope of the variable and can have significant implications for your program.
Global Variables
A global variable is a variable that is defined outside of a function and can be accessed throughout the entire program. Global variables can be used anywhere in your code, making them convenient for storing frequently used values.
For example, let’s say you have a program that has many functions that all use the same company name. Instead of typing out the company name each time, you can define a global variable and use it throughout your program.
Here’s an example of how to create a global variable:
“`
company_name = “ABC Inc.”
“`
You can now use this global variable in any function in your program by calling `company_name.`
Local Variables
A local variable is a variable that is defined inside a function and can only be accessed within that function. Local variables are temporary and only exist as long as the function is being executed.
For example, let’s say you have a function that calculates the area of a rectangle. To calculate the area, you need the length and width of the rectangle. You can define these variables as local variables within the function.
Here’s an example of how to create local variables:
“`
def rectangle_area(length, width):
area = length * width
return area
“`
In this function, `length` and `width` are two local variables. The `area` variable is also a local variable because it is defined within the function. These variables cannot be accessed outside of the function.
When to Use Global or Local Variables
It’s important to understand when to use global or local variables in your coding.
Global variables are useful when you have values that are used frequently throughout your program. However, overusing global variables can lead to confusion and potential bugs.
Local variables are useful when you only need a value within a specific function or section of your program. They also help prevent bugs by limiting the scope of the variable.
In conclusion, understanding the difference between local and global variables is critical when coding in Python. Proper use of variables can significantly improve the efficiency and readability of your program.
Table difference between local and global variables in python
| Local Variables | Global Variables |
|---|---|
| In Python, local variables are declared inside a function and can only be accessed within the same function. | Global variables are declared outside a function and can be accessed from any part of the code, including inside functions. |
| If a local variable has the same name as a global variable, the local variable takes precedence and the global variable is ignored. | If there is a conflict between a local variable and a global variable with the same name, the local variable takes precedence within the function that declares it. However, the global variable retains its value outside of that function. |
| Local variables are created when the function is called and are destroyed when the function exits. | Global variables are created when they are first defined and exist until the program terminates. |