C++ Header Files

The C++ standard library contains files containing the standard functions that your program may use. These files are known as header files. Header files provide function prototype definitions for library functions. Data types and constants used with the library functions are also defined in them.

Let's discuss some important header files of Borland C++.


This header files defines types and macros needed for the standard I/O package. This file also defines the standard I/O predefined streams i.e., stdin, stdout, stdprn, and stderr. When you include iostream.h file in your program, this file i.e., stdio.h automatically gets included in your program. The standard I/O functions contained in stdio.h are given in the following table :

clearerr fclose fcloseall fopen feof
feror fflush fgetc fgetchar fgetpos
fgets fileno flushall fopen fprintf
fputc fputchar fputs fread freopen
fscanf fseek fsetpos -fsopen ftell
fwrite getc getchar gets getw
perror printf putc putchar puts
putw remove rename rewind rmtmp
scanf setbuf setvbuf sprintf -strerror
strerror tempnam tmpfile tmpram ungetc
vfprintf vfscanf vprintf vscanf vsprintf


This header file declares the basic C++ streams I/O routines. Some of the functions defined in it are :

open close get getline read
write put seekg seekp tellg
tellp ignore peek putback flush
rdstate bad eof fail good


This header file declares several string manipulation and memory manipulation routines. The functions contained in string.h are given in the following table:

memccpy memchr memcmp memcpy
memicmp memmove memset movedata
movemem stpcp strcat strchr
strcmp strcoll strcpy strcspn
strdup strerror stricmp strcmpi
strlen strlwr strncat strncmp
strncmpi stncpy strnicmp strnset
strpbrk strrchr strrew strset
strspm strstr strtok strupr


This header file declares prototypes for the math functions and math error handlers. The routines in math.h file perform mathematical calculations and conversion.

acos acosl asin asinl atan
atanl atan2 atan2l atof cabs
cabsl ceil ceill cos cosl
cosh coshl div exp expl
fabs fabsl fevt floor floorl
fmod fmodl frexp fexpl hypot
hypoll dexp ldexpl ldiv log
logl logio log101 matherr _matherrl
modf modfl poly polyl pow
polywl powlo pow101 sin sinl
sinh sinhl sqrt sqrtl tan
tanl tanh tanhl


This header file declares several commonly used routines like conversion routines, search/sort routines, and other miscellaneous things. Some of its functions are :

_fullpath _makepath _searchenv _splitpath
atof atoi atol ecvt
fcvt gevt itoa ltoa
_strdate _strtime strtod strtol
_strtoid strtoul ultoa mblen
mbtowc wcstombs wctomb abs
labs _irotl _irotr calloc
coreleft free malloc realloc


This header file declares the C++ streams I/O manipulators and contains macros for creating parameterised manipulators. Some of its functions are :

dec endl ends flush
hex oct reset/osflags setbase
setfile setiosflags setprecision setw

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