What is library in C++ Language ?

In a programming language, a library is a collection of subprograms used to develop software. Libraries are not independent programs, rather they are helper code used in other independent programs.

C++ Header Files :

The C++ standard library contains files containing the standard functions that your program may use. Header files provide function prototypes, definitions for library functions. Let us discuss some important header files :

stdio.h

This header file defines types and macros needed for the standard I/O packed. When you include iostream ( iostream.h ) file in your program, this file stdio.h automatically gets included in your program. The standard I/O functions contained in stdio.h are given below :

1. clearerr
2. fclose
3. fcloseall
4. fdopen
5. feof
6. ferror
7. fflush
8. fgetc
9. fgetchar
10. fgetpos
11. fgets
12. fileno
13. flushall
14. fopen
15. fprintf
16. fputc
17. fputchar
18. fputs
19. fread
20. freopen
21. fscanf
22. fseek
23. fsetpos
24. fsopen
25. ftell
26. fwrite
27. getc
28. getchar
29. gets
30. getw
31. perror
32. printf
33. putc
34. putchar
35. puts
36. putw
37. remove
38. rename
39. rewind
40. rmtmp
41. scanf
42. setbuf
43. setvbuf
44. sprintf
45. -streror
46. strerror
47. tempnam
48. tmpfile
49. tmpram
50. ungetc
51. vfrintf
52. vscanf
53. vprintf
54. vscanf
55. vsprintf

string.h

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

1. memccpy
2. memchr
3. memcmp
4. memcpy
5. memicmp
6. memmove
7. memset
8. movedata
9. movemem
10. stpcp
11. strcat
12. strchr
13. strcmp
14. strcoll
15. strcpy
16. strcspn
17. strdup
18. strerror
19. stricmp
20. strcmpi
21. strlen
22. strlwr
23. strncat
24. strncmp
25. strncmpi
26. stncpy
27. strnicmp
28. strnset
29. strpbrk
30. strrchr
31. strrew
32. strset
33. strspm
34. strstr
35. strtok
36. strupr
37. strxfrm

math.h

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

1. acos
2. acosl
3. asin
4. asinl
5. atan
6. atanl
7. atan2
8. atan21
9. atof
10. atof
11. cabs
12. cabsl
13. ceil
14. ceill
15. cos
16. cosl
17. cosh
18. cosh1
19. div
20. exp
21. expl
22. fabs
23. fabsl
24. fevt
25. floor
26. floorl
27. fmod
28. fmodl
29. frexp
30. fexpl
31. hypot
32. hypoll
33. dexp
34. ldexpl
35. ldiv
36. log
37. logl
38. logio
39. log101
40. matherr
41. _matherrl
42. modf
43. modfl
44. poly
45. poly1
46. pow
47. polywl
48. powlo
49. pow101
50. sin
51. sinl
52. sinh
53. sinh1
54. sqrt
55. sqrtl
56. tan
57. tanl
58. tanh
59. tanhl

stdlib.h

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

1. _fullpath
2. _makepath
3. _searchenv
4. _splitpath
5. atof
6. atoi
7. atol
8. ecvt
9. fcvt
10. gcvt
11. itoa
12. Itoa
13. _strdate
14. _strtime
15. strtod
16. strtol
17. _strtoid
18. strtoul
19. ultoa
20. mblen
21. mbtowc
22. _wcstombs
23. wctomb
24. abs
25. labs
26. _irotl
27. _irotr
28. calloc
29. coreleft
30. free
31. malloc
32. realloc

iostream.h

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

1. open
2. close
3. get
4. getline
5. read
6. write
7. put
8. seekg
9. seekp
10. tellg
11. tellp
12. ignore
13. peek
14. putback
15. flush
16. rdstate
17. bad
18. eof
19. fail
20. good
21. clear

iomanip.h

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

1. dec
2. endl
3. ends
4. flush
5. hex
6. oct
7. reset
8. osflags
9. setbase
10. setfile
11. setiosflags
12. setprecision
13. setw
14. ws

Note : Here we mix/shuffle all header file's options with 2 colors , cause if all options is belong some color then we think some time reader confused which one he read or which one not (mistake) so, here we use 2 type colors.