Local and Global Variables

1.) Local Variable:

A local variable is a variable that is declared inside a function or a block and is accessible only within that function or block. It cannot be accessed outside its scope.

Characteristics:

• Declared inside a function or block.
• Scope is limited to the block where declared.
• Memory is allocated when the block is entered and deallocated when the block is exited (automatic storage).
• Not visible outside its function.

Example:

#include <stdio.h>

void display() {
    int x = 10;  // Local variable
    printf("x inside display(): %d\n", x);
}

int main() {
    // printf("%d", x); // Error: x not declared in this scope
    display();
    return 0;
}

2.) Global Variable:

A global variable is declared outside of all functions (usually at the top of the program) and is accessible from any function in the program.

Characteristics:

• Declared outside any function.
• Scope is throughout the entire program.
• Memory is allocated when the program starts and deallocated when the program ends.
• Can be modified by any function (use with caution).

Example:

#include <stdio.h>

int y = 50;  // Global variable

void display() {
    printf("y inside display(): %d\n", y);
}

int main() {
    printf("y inside main(): %d\n", y);
    display();
    return 0;
}

Scope, Visibility, and Lifetime of Variables: