C Programming - Declarations and Initializations - Discussion

The extern keyword means "declare without defining". In other words, it is a way to explicitly declare a variable, or to force a declaration without a definition. It is also possible to explicitly define a variable, i.e. to force a definition. It is done by assigning an initialization value to a variable. If neither the extern keyword nor an initialization value are present, the statement can be either a declaration or a definition. It is up to the compiler to analyse the modules of the program and decide.

If we declare any functions external as well as an internal function in same code then if latter that function is called from anywhere in file the which function will be loaded? how is the issue of function resolved in these scenario? can anyone please explain these to me?

Then 'extern' keyword not understand, please explain.

Global function is nothing but the variables which are used for overall program. Where as local variables are used in specific function or a specific part of the program.

Hi sir you said extern is globally declared where as int fun you said localy declared so how you can so it is not different.

@Nancy: http://wiki.answers.com/Q/What_is_the_use_of_extern_in_C

"Declaring a variable as extern will result in your program not reserving any memory for the variable in the scope that it was declared."

While using extern keyword, memory is allocated to variable or not?

The extern int fun(); is nothing but it can be declared globlly means out side the function.

But int fun(); can be declared in local means in the function only.

extern refers to suppose inside a local variable in main() we can access outside this variable its called extern and the same as fun() can be accessed
syntax:
main()
{
extern int s; //external declaration
}
fun1()
{
extern int s; //external declaration
}

int y; //definition

'extern' is similar to the gloabal declaration we can access any where in the program module, similar to accessing the functions in .dll files from various .exe files.