C Programming language

# Function

A fuction is a self contained block of statement that perform a coherent taskof some kind.

• Functions are a powerful programming tool
• A function is a block of code that performs a specific task
• It has a name and it is reusable
• It can be executed from as many different parts in a Program as required, it can also return a value to calling program
• All executable code resides within a function
• It takes in input, does something with it, then give the answer
• A C program consists of one or more functions, A computer program cannot handle all the tasks by it self
• It requests other program like entities called functions in C
• We pass information to the function called arguments which specified when the function is called
• A function either can return a value or returns nothing. Function is a subprogram that helps to reduce coding

Defining a Function

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 function_name( parameter list )
{
   body of the function
}

# return_type: A function may return a value. The return_type is the data type of the value the function returns. Some time the return_type is the keyword void, in that case functions perform the desired operations without returning a value.

# function_name: This is the actual name of the function

# Parameters: Its like placeholder. Parameters are optional; that is, a function may contain no parameters. When a function is invoked, you pass a value to the parameter. The parameter list refers to the type, order, and number of the parameters of a function

# Function Body: The function body contains a collection of statements that define what the function does

Note:

• If a program contain only one function , it must be main()
• If a program contain more than one function then one must be main()
• Each function in a program is called sequence specified by the function calls in main()
• A function can be called from other function but can not be defined in the other function