C Programming - Declarations and Initializations - Discussion

Here, int a=20; is outside of the main() then how come its possible?

Here, extern int a is for globally declared functions not for locally declared functions. Here, int a = 20 is declared outside means global therefore it can be accessible by the extern prototype.

extern int a;

This statement is valid only when the variable is present globally in other file programmer it is local or global variable to same programme and the file in which the variable is declared must be included in the programme otherwise we will get an error.

The declaration of the variable is after the variable is used, is that valid? You can declare outside the main function, that's the global variable concept, but in that sequence, do we get that output?

a is declared outside the function. How can get the answer 20?

How it is print 20. A is initialized outside the function.

For the given question 'a' declared in local variable section so it first search and take the 'a' value first if we don't declare the 'a' value in the program it takes the value 0 because we declare return 0;

Extern int a;

Above line states that a is an integer variable and extern show that it contain in another files where there is no any integer a, so a=20; is local for this files.

Therefore output of this program is 20.

How could we use a=20. It is declared outside the main function.

I have the perfect solution

#include<stdio.h>
#include<conio.h>
int a=20;
int main()
{

printf("%d\n", a);
getch();
}

In the above expression a is declared globally. so we can access the variable 'a' any where in the programme and we don't have to declare it inside of the programme.

But in case of the following programme:

#include<stdio.h>
#include<conio.h>
int main()
{
int a;
printf("%d\n", a);
getch();
}
int a=20;

The variable a is declared externally. Means we can initialize 'a' outside of the programme.

But the twist is that we also have to declared it locally in the programme otherwise we will get a error.

This is also a difference between global and extern variable.