In this article, you will find a standard list of C++ header files (with their brief instruction & uses). Each header file have their functions. These functions are called built-in functions of programming language that are used for different kinds of purposes. Before using these functions we should have knowledge about them. So read this article completely to clear the concept about C++ header files & their functions.

## What are built-in Functions

The built-in functions are part of the C++ programming language. These are ready-made small program (or functions) in C++. The built-in functions of C++ (or C) are declared in different header files. C++ provides many built-in functions to solve various types of problems. The programmer uses built-in functions in writing program to perform various tasks. This saves the rogrammer’s time from writing his/her own functions. It is also reduce the source code of the program.The built-in functions contains in a header file of C++ programming language. Before using them in the program we have to declare header file that have these functions. For example, the "canio.h" header file must be declared before using "clrscr();" function.

### 1. The "canio.h" header file

The word “conic" stands for console input/output. The “conio.h” header file contains various basic input and output built-in functions. Some commonly used functions of this header file are as follows:- The clrser( ) Function
- The clreol( ) Function
- The getch( ) Function
- The getche( ) Function
- The kbhit( ) Function
- The gotoxy( ) Function

### 2. The "stdio.h" Header File

The word “stdio” stands for standard input/output. This header file contains various standard input and output functions. These functions are used to get input from the input device and to print/display the output on the output device. The most important and commonly used functions of 'stdio.h' header file are as follows:- The getchar( ) Function
- The putchar( ) Function
- The gets( ) Function
- The puts( ) Function

### 3. The "math.h" Header File

This header file contains various mathematical functions. These functions are used to perform mathematical operations. The most important and commonly used functions of this header file are given below:- The abs( ) Function
- The fabs( ) Function
- The sqrt( ) Function
- The pow( ) Function
- The floor( ) Function
- The ceil( ) Function
- The fmod( ) Function
- The cos( ) Function
- The sin( ) Function
- The tan( ) Function
- The log( ) Function
- The log10() Function

### 4. The "ctype.h" Header File

This header tile contains various built-in functions that are used to find out the types of different characters or values. It also contains functions used to convert lowercase letters to uppercase letters and vice versa. The most important and commonly used functions of this header file are as follows:- The isalpha() Function
- The isalnum() Function
- The isdigit() Function
- The isxdigit() Function
- The islower() Function
- The isupper() Function
- The isascii() Function
- The isspace() Function
- The isprint() Function
- The iscntrl() Function
- The ispunct() Function
- The toascii() Function
- The tolower() Function
- The toupper() Function

### 5. The "string.h" Header File

This header file contains the string related built-in functions. These functions are used to process strings. The most important and commonly used string functions of this header file are described as under:- The strlen() Function
- The memcmp() Function
- The memicmp() Function
- The strcmp() Function
- The stnicmp() Function
- The strncmp() Function
- The strnicmp() Function
- The strspn() Function
- The strcspn() Function
- The strcoll() Function
- The strstr() Function
- The memchr() Function
- The strchr() Function
- The strrchr() Function
- The strpbrk() Function
- The strrev() Function
- The memset() Function
- The strset() Function
- The strnset() Function
- The strlwr() Function
- The strupr() Function
- The memcpy() Function
- The memmove() Function
- The strcpy() Function
- The strncpy() Function
- The strdup() Function
- The strcat() Function
- The strncat() Function
- The strtok() Function

## C++ Graphics Mode Functions

In C++ programming language, we can create different objects such as lines, circles, rectangle and many other shapes using various graphics built-in functions. The commonly used graphics functions used to create graphics objects are as follows:

- The circle() Function
- The arc() Function
- The pieslice() Function
- The putpixel() Function
- The getpixel() Function
- The line() Function
- The rectangle() Function
- The setlinestyle() Function
- The bar() Function
- The har3d() Function
- The getimage() Function
- The putimage() Function

## C++ Graphics Text Mode Functions

In graphics mode, text can also be displayed in different fonts, styles, sizes, colors and directions. The graphics functions that are commonly used to create and print text are as follows:

- The outtext() Function
- The moveto() Function
- Tlie outtextxy() Function
- The settextstyle() Function
- The setcolor() Function
- The setbkcolor() Function.