C Programming - Declarations and Initializations - Discussion

@Vikas.

defining and initializing
int a=20;

defining without initialization :
int a;

initializing already defined variable a
a=20;

What is the difference between initializing and defining?

Prototype means: Gives a function name and args types.

For eg:sum funcall (10, 20), where funcall is an prototype means function name. Where does omit about the interior body of that function.

Prototypes are just like declarative statements which tell the compiler that the type of the input and type of the parameter and what the function is doing. They are like interface to complier.

How we says that prototyping is the declaring?

Can you people explain the difference between old compiler and new compiler?

Definition of prototype means declaration of function. It's tell the compiler -this type of function are used in a program.

Prototype means declaration of function which is specially use in the program.

Is initialization and Definition of varible same?

Initialization means declaration and assignment, like int a=10;

Definition means just like ... int a; here memory space is allocated by the OS at the run time , and if initialization means that value goes to the reserved memory.

Then you may have a doubt what is declaration? Isn't the statement int a; is the declaration itself? Answer is NO, int a;is defenition, int a=10; is initialization ..and the declaration is like extern int a;

Here what happens is no memory space is allocated for 'a', Its simply telling the compiler that variable 'a' is a type of 'int' and you should define it if you want to use it.. like int a; again...