What are the differences between global variables and local variables in C programming language?

There are differences between global variables and local variables in the C language.

Scope: The scope of global variables is the entire program, and they can be used in any function; whereas the scope of local variables is limited to the function where they are defined and cannot be accessed outside of that function.

Lifetime: The lifetime of a global variable is the entire duration of the program’s execution, beginning when the program starts and ending when the program ends. In contrast, the lifetime of a local variable only exists during the execution of the function it belongs to and is destroyed once the function finishes executing.

Memory allocation: Global variables are allocated in the static storage area during program execution, meaning that the memory space for global variables is allocated when the program starts running. On the other hand, local variables are allocated on the stack during function calls and are automatically released after the function call ends.

Global variables are automatically initialized to 0 or null if not explicitly assigned, while local variables must be manually assigned before use as they are not automatically initialized.

Global variables can be accessed and modified anywhere in the program, while local variables can only be accessed and modified within the function where they are defined.

Purpose: Global variables are generally used to share data among multiple functions, while local variables are typically used to temporarily store data within a function.