What is a Function in C?

A function is a group of statements that work together to complete a certain goal. Every c program contains one or more than one functions. Because it is the starting point of your C code, where your program is performed, the main() function is a must for the C programming language.

Huge C programs are broken down into fundamental building elements known as C functions. A C function is a collection of instructions surrounded by the symbol "" that carry out a particular task in a C program. Actually, a C program is created by the collection of these functions.

Why Functions are used in C?

A program's fundamental building elements are C functions. All C programs use functions to enhance their capacity to be reused, understood, and maintained.

Syntax for the functions in C

The syntax for declaring the function in c is given as

return-typefunction_name(arguments)
{
Block of statements;
Return statement;
}

Explanation:

Optional return types, arguments, and return statements
In practice, it is unnecessary to specify the return statement anytime a function returns a value. In this instance, a warning message with the subject line "function should return a value" will appear.
Every time the function returns a value, collecting the value is not required

Classification of Functions

Functions are classified into two types

Library function
User-defined function

1. Library function

These library functions are present in each and every header that can be used in a program. some of the header files given below

scanf()
printf()
gets()
puts()

2. User-defined function

The user is required to create user-defined functions while developing a program and it minimizes the code and decreases the complexity of a large programme.

Function Features

There are types of features. They are

Function definition
Function call
Function declaration

1. Function definition

The actual statements that must be executed are contained there. The most crucial component is the one over which the function has control. Here the function returns only one value.

Syntax:

return-type function_name(arguments)
{
function body;
}

2. Function call

Throughout the program, functions can be invoked from anywhere. Function declaration and function call cannot have different parameter lists. The number of functions that must be sent must match the number indicated in the function declaration.

Syntax:

function_name(arguments);

3. Function declaration

A function must be declared globally in a C programme so that the compiler is aware of the function name, function parameters, and return type.

return-type function name(arguments) is the syntax.

Function Categories

A function may or may not accept an argument. It might or might not provide any benefit in return.These facts lead to the conclusion that function calls have four different characteristics.

without return value and without parameters
with a return value and without parameters
with parameters and without return value
with parameters and with return value

Advantages of Functions

We can avoid rewriting application code by using functions.
We can create an application in module structure by using functions.
By using the function, program development will be simplified.
When an application is developed in module format, it is simple to trace and debug the programs.
We may track the program's logic implementation by using the functions.
Code reuse is the function's primary goal.
A c program is made up of several functions.
We can call any other function from any other function.
The process of compilation will always go top to bottom.
The main will be the sole variable used during execution, from beginning to end.
To avoid a compilation problem during implementation, we must use a forward declaration, or prototype, when using a function that was defined later.
Function declaration calls for the specification of the return type, function name, and parameter type information.
The initial line of a function definition is referred to as the function declarator or function header.
If a function never returns any values, then specify void as the return type.
Whenever a function returns a value during implementation, the return type must be specified as the return value type. i.e., a return statement of the same type as the value we are returning is necessary.
The function's default parameter type is void, and its default return type is an int.

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