Introduction to Functions in C

This “Introduction to Functions in C” page providing introduction to functions including definition, advantages of functions in programming languages.



  • A function is a block of code that performs a specific task.
  • It has a name and it is reusable.
  • Function taking input, processing input and produce output.
  • It can be accessed from as many different parts in a C Program as required.


Why functions?

  • The main advantage of function is code re-usability.
  • Using functions we can implement modularity programming.
  • The use of user-defined functions allows a large program to be down into a number of smaller, self-contained components, each of which has some unique, identifiable purpose.
  • Thus a C program can be modularized through the intelligent use of such functions.


Functions Classified into: 

  1. Built In Functions
  2. User Defined Functions


Built in Functions:

  • C-language has library.
  • Library is a collection of header files.
  • Header file is a collection of pre-defined functions.
  • These functions are also called as ‘library functions’.
  • Examples…


User Defined Functions: 

  • A programmer defined function depends on application requirement.
  • Need to follow syntactical rules to define a function.
  • It is possible for the programmer to define user header files.
  • Example…
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