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09 HEADER FILES AND
LIBRARY FUNCTIONS
Your Aim
to learn about:
Header Files Functions of math.h Header File
Functions of stdlib.h Header File More Solved Programs
As you already know that C++ provides built-in functions. Built-in functions are defined inside
the header files. Hence, these functions are also called library functions. C++ provides a number
of header files to perform different types of operations like mathematical calculations, character
manipulations, input/output and error checking.
HEADER FILES
A header file can be defined as a collection of predefined functions which you can use to increase
your program’s productivity and save your programming time. These header files comes in-built
with the C++ compiler. Hence, these are known as standard header files and the functions they
contain are called standard library functions. Generally, all the header files in C++ have the .h
extension. C++ provides several header files. Some of them are as follow:
Header File Description
iostream.h It provides standard input and standard output functions.
conio.h It provides functions for console input/output.
math.h It provides various functions to perform mathematical operations.
ctype.h It provides functions to handle characters in C++.
stdlib.h It provides various functions to perform operations like numbers
to text conversion, text to numbers conversion, memory allocation,
random numbers and various other utility functions.
To use any library function in your program, respected header file should be included at the beginning
of your program code. You can include a header file in your program by using the preprocessor
directive #include followed by name of the header file in between the angular brackets:
#include <iostream.h>
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