C Programming - Declarations and Initializations - Discussion

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

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

Prototype is nothing but an outlook, by seeing it we can able to understand what is the matter that it is going to represent in the program. It just says the information about a particular declared variable or a function. I think your dbt was clarified.

What is prototype?

What does exactly prototype mean?

Prototyping means declaring a function.
Now What is declaration and definition?

In term of variables:

extern int a; //It is a declaration. Declaration means variable is not present at that time in memory.It will come in memory at the time of execution.

int a; //It is a declaration as well as definition. Definition means variable is present in memory. Where extern tells the compiler that a variable of type int and named 'a' will be linked to the program at runtime.

In term of Functions:

extern int fun(); //it is a prototype which tells the compiler that a function named 'fun' which will be linked at runtime may be present in the same file or outside the file.

int fun(); //it is a prototype which tells the compiler that a function named 'fun' which will be linked at runtime will be defined in the same file.

What is the difference between prototyping and declaration ?

A function call is an expression containing a simple type name and a parenthesized argument list.

What is the calling function?

Declaration is the process of declaring the variable with some special name and its data-type,scope,memory storage etc. and definition is actually assining some value to that variable.

In case of function declaration is defining its prototype and declaration is code where we specify what the function actually does.

Examples:

case 1) variable

Variable Declaration:
int a,b[10];

Variable Definition:
a=1, b={1,2,3,....};


Function Declaration:
void display();

Function Definition:

void display()
{
printf("......");
}