Question

What is the scope of a global variable?

Short answer

A global variable is a variable that is globally accessible, meaning it can be accessed from any part of the program, since it is declared outside of all functions or classes. This is contrary to a local variable which is only accessible within the specific function or class it is declared within. What is the difference between a global and local variable? The main difference between a global and local variable is their scope i.e., the parts of the program where they can be accessed. A global variable can be accessed by any function or class in the program as it's declared outside the functions or classes. On the other hand, a local variable is only accessible within the specific function or class it is declared within. Why are global variables often discouraged? Global variables might be useful when multiple functions or classes need to access or modify the same value but are often discouraged due to their potential for misuse which can lead to confusion and conflicts in the code. They can also cause unintended side effects. It is generally recommended to make use of local variables as much as possible to maintain better control over your code.

Step-by-step solution

Definition of Global Variable

A global variable is a variable that is declared outside of any function or class in a program. It is accessible from any part of the program, which means its scope extends throughout the entire code.

Global Variable vs Local Variable

A local variable is declared within a function or a class and is only accessible within that specific function or class. On the other hand, a global variable can be accessed by any function or class in the program, making it more widely available.

Modifying a Global Variable

To modify a global variable from within a function or class, the 'global' keyword should be used before the variable name. This keyword tells the program that you are referring to the global version of the variable, rather than a local version that may exist within the function or class. Example: ```python count = 0 # This is a global variable def increment_count(): global count # Referencing the global variable 'count' count += 1 increment_count() print(count) # Output: 1 ```

Advantages and Disadvantages

A global variable can be useful when multiple functions or classes need to access or modify a shared value. However, the use of global variables should be limited because they can easily be misused or lead to confusion, as well as potential conflicts in the code. It is generally recommended to use local variables as much as possible for better control over the code and to avoid unintended side effects.