Introduction to Function

With this post we are moving on to the advance topics of C language.
In this post, I am going to discuss one of the most important concept of modern programming languages i.e Function. So let’s dive in.

A function is a block of code that performs a specific task.

When a set of related executable statements are places within a group then it is referred to as function.
We can use functions for the operations which are need to be repeated.

C functions can be classified into two categories:

Library functions are provided by the C programming language.
They are also knows as in-built or ready-made functions.
User need not to define them. User can directly use them in the program.
Some examples of library functions are : printf(), scanf(), strlen(), gets(), clrscr(), etc.

User-defined functions are those functions which are written by the user (programmer).
Similar to variables, they need to be defined before using them because compiler dos not have knowledge about them.
main() is an example of user-defined functions.

One of the major advantages of functions is re-usability.
There are situations in which we need to perform some operations or calculations multiple times. If we do not use functions, we have to rewrite that code again and again.
In such cases, function helps a lot. We can reuse the code which is already written. There is no need to rewrite that code again and again.
Function works on the principle “write once, use multiple times”
So this way, we have to write the functions once and it can be used for multiple times.

Function provides modularity into program by dividing large programs into smaller parts called modules.
These modules can easily be coded, tested and debugged separately.
Development will be fast since modules can be assigned to multiple programmers.
Each programmer is responsible to code, test and debug modules assigned to him or her only.
Programmers can work on the different modules of the same projects simultaneously.

Programs divided into functions can be easily debugged.
Since programs are sub-divided into modules, individual modules are coded, tested and debugged separately.
If any error is found or modules do not work properly, we only need to check the modules responsible for that task.
We need not to check the whole program starting from the scratch.
Since each module is small and implements limited functionality, they are easy to code, debug and modify.
It saves both time and labor.

Project management becomes easy as different modules are assigned to different team of programmers.
Programmers can work on separate modules simultaneously on the same projects.
Since task is divided into smaller modules, it becomes easy to handle and manage.

Programs are divided into different smaller modules and these modules further can be sub-divided for better understanding.
Programs written through functions allow better readability.
They are easy to read and understand.
It helps to understand program flow and logic.

That’s it for this post. Elements of Function will be discussed in the next post so please stay tuned!