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Built-In Function: Definition & Examples

There are certain tools that simplify the coding process, saving developers from reinventing the wheel. One such indispensable tool is the built-in function. This blog post aims to demystify what built-in functions are, how they operate, their purpose, and provide some concrete examples for better understanding.

What is a built-in function?

Built-in functions refer to those pre-defined functions that come along with a programming language. They are intrinsic components of the language’s library, ready to be used without requiring any additional installation or importation. These functions have been designed to perform common tasks, thus facilitating efficient and swift coding.

How does a built-in function work?

A built-in function operates just like any other function. It takes in arguments, performs certain operations, and then returns a result. The major difference lies in the fact that these functions are already defined within the programming language, eliminating the need for the programmer to define them explicitly.

Purpose of built-in functions

The main purpose of built-in functions is to enhance efficiency and productivity in programming. They render certain tasks easier and quicker to accomplish, thereby reducing development time. Moreover, they contribute to code readability and maintainability as they are standardized and well-documented.

15 examples of built-in functions

Let’s look into some specific examples of built-in functions across various programming languages.

  1. print() – A commonly used built-in function in Python, print() outputs the specified message to the screen.
  2. len() – This Python function returns the number of items in an object like a list or a string.
  3. max() – Another Python staple, max() extracts the maximum value from a list or array.
  4. abs() – In Python, abs() provides the absolute value of a given number.
  5. type() – This function in Python returns the data type of the object passed as an argument.
  6. parseInt() – A JavaScript built-in function, parseInt() converts a string into an integer.
  7. isNaN() – This JavaScript function checks if a value is NaN (Not a Number).
  8. encodeURI() – In JavaScript, encodeURI() encodes a Uniform Resource Identifier (URI) by replacing each instance of certain characters with one, two, three, or four escape sequences representing the UTF-8 encoding of the character.
  9. alert() – A simple JavaScript function, alert() creates a pop-up alert box with a specified message.
  10. charAt() – This Java function returns the character at a specific index in a string.
  11. length() – In Java, length() gives the length of a string.
  12. sqrt() – A built-in function in C++, sqrt() calculates the square root of a number.
  13. pow() – This C++ function computes the power of a number.
  14. exit() – In C++, exit() terminates a program.
  15. tolower() – This C++ function converts a character to lowercase.


Built-in functions are powerful tools that significantly streamline the coding process. They encapsulate common tasks into simple, reusable components, eliminating repetitive code and fostering cleaner, more efficient programming. By understanding and effectively utilizing these built-in functions, programmers can elevate their coding prowess to new heights.

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