Function,Argument and Parameter in C

Function is a group of statements which together perform a task. Every C program has at least one function, that is the main (), and all the most trivial programs may specify additional functions.
You can divide the code into a separate function. How do you divide your code between different functions up to you, but logically division usually once every function performs a specific task.
A function declaration tells the compiler about the name of this function, the return type, and parameters. A definition of functions providing the actual body functions.
C standard library provides a variety of built-in functions that you can call the program. For example, the function strcat () to combine two strings, the function memcpy () to copy one memory location to another location and more functions.
Function known by various names such as methods or sub-routine or procedure, etc.

Defining a Function:

The general form of a function definition in C programming language is as follows:
A function definition in C programming language consists of a function header and a function body. Here are all the parts of a function:

• Return Type: A function may return a value. The return_type is the data type of the value the function returns. Some functions perform the desired operations without returning a value. In this case, the return_type is the keyword void.
• Function Name: This is the actual name of the function. The function name and the parameter list together constitute the function signature.
• Parameters: A parameter is like a placeholder. When a function is invoked, you pass a value to the parameter. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the parameters of a function. Parameters are optional; that is, a function may contain no parameters.
• Function Body: The function body contains a collection of statements that define what the function does.
   

Function Arguments:

If a function is to use arguments, it must declare variables that accept the values of the arguments. These variables are called the formal parameters of the function.
The formal parameters behave like other local variables inside the function and are created upon entry into the function and destroyed upon exit.