C Programming - Declarations and Initializations - Discussion

Thanks for your explanation @Venkat.

#include<stdio.h>
int a;
int a;
int a;//several declarations;
main()
{
printf("%d\n",a);
}
output: 0.
---------------------------------------------------------------------------------------------
#include<stdio.h>
int a;
int a=2;
int a=3;//several definations
main()
{
printf("%d\n",a);

output:user@user:~/c$ cc t.c
t.c:4:5: error: redefinition of \'a\'
t.c:3:5: note: previous definition of \'a\' was here

---------------------------------------------------------------------------------------------
#include<stdio.h>
int a;
int a=2;//single defination
int a;
main()
{
printf("%d\n",a);
}
output: 2.

It's not cleared. Please explain clearly.

Please elaborate with an example, how can a global variable have multiple declarations with one definition only?

Once we declared variable globally then we can access it directly anywhere without declaring it again and again.

But there is no use of declaring it several times even if we can.

That means if we use an variable from other file which is globally defined once in that file. Every time when you are using that variable you have do declare that as extern. That means we can declare many times for ones defined global variable.

Please elaborate with an example. So that I can get it clearly.

Thanks in advance.