Local vs Global variables in C

The following image briefly explains the significant differences between local & global variables in C.

Local variable	Global variable
1. Variables declared inside the function.	1. Variables declared outside the function.
2. Scope is throughout the block.	2. Scope is throughout the program.
3. Memory allocated in the stack frame of the function in which it is declared and it is valid till function finishes the execution.	3. Memory allocated in the .data section of a program and it is valid till the program finishes execution.
4. Can only be accessed from inside the block in which we declared it.	4. Can be accessed by all the functions in the program.

Local variable example

#include <stdio.h>
int main()
{
    fun();
    return 0;
}

int fun()
{
    // local variables
    int a = 20;
    int b = 30;
    int c = 40;
}

#include <stdio.h>

// global variable
int a = 10;

void main()
{
    printf("Printing in main %d", a);
}

Categorized in:

Tagged in: