Windows Programming > why unicode is important before you start to program

Why UICODE is important before you start program

First of all you must have question in mind:
What is UNICODE?
Unicode is a coding system in which each character is stored in 2 bytes (16bits) rather than simple 8 bit character. Usually the characters you see on a standard english keyboard are stored in one byte, to test it, you simply create new text file in notepad and type only one character in it, then save an check its size, it will report 1 byte.

Why is it important for Windows Programmers
When your applciation is enabled to compile with UNICODE as well as NON-UNICODE fucntions, then you have covered good range of Microsoft operating systems.
Windows 98 accepts applications of non-unicode and Windows NT, XP, and Vista run all unicode applications natively, but they do accomodate non-unicode applciations too. So, when also compiling your software also for windows 98/95 gives chance for users who are still running old operating systems, that may result in good business too.

For example, you have developed an Office Automation tool, that you sell to Windows NT, 200, XP, and Vista users, but do not provide a version for windows 98 and 95 users, so you are not covering full range. By providing all users same applciation, you are indirectly giving them idea to swith to new operating system too. And obviously increase in business.

Single byte storage
Now problem with 1 byte character storage is, it can store maximum value of 255 in 8 bits, so can store maximum 255 different characters in each byte. To solve this problem (keeping in view the international language) new system was introduced called 'unicode'. Using this system, we can store character in 2 bytes (16 bits), which gives us possibity to store huge variety of different values upto 65535. E.g. from range of 1665 to 1773 there are some arabic language characters.
On the webpages to display this kind of characters you use &#THENUMBER; where 'THENUMBER' is the numaric value of the character.

Let's come to the point. There are two kind of functions in windows api, the first one are non-unicode and the other are unicode. For example the function MessageBox is defined two way in windwos API, one MessageBoxA and second MessageBoxW, the one with 'A' on end is non-unicode version whcih accepts text defined using CHAR array, and the other one with ending 'W' is the unicode one which accepts wide character.

Very simple to understand is use types:

CHAR for non-unicode and
WCHAR for unicode application

NOTE:

If you are using dev c++, your applciation is by default non-unicode, to enable it compile as unicode applciation simple put 2 defines on top of all the code as


#define UNICODE
#define _UNICODE

And, if you are using Microsoft Visual Studio Express Edition, then your applciation is by default UNICODE enabled, to enable your application compile as non-unicode put 2 undefines on top of all code as


#undef UNICODE
#undef _UNICODE

Besides, Mircorsoft Visul Studio provides a very good project options panel, through which you can change these settings, either to compile as UNICODE or Multibyte characterset applciation.

So, do I have to maintain two separate source coes for same applciations?

NO, the best solution is use TCHAR, as:

TCHAR myStrVar;
NOTE: you might need ot include <tchar.h> if you are using a compiler other than Microsoft Visual Studio

And, enclose every character string within a macro _T( ), that acts as per current characterset accordingly.

e.g. Following code will compile as both unicode and non-unicode applciation:

MessageBox(NULL,_T("My test message"),_T("My test title"),0);

PROBLEMS

1.strcat and other standard string manipulation functions seem to be not compiled when compiling as UNICODE enabled, why?
Well, when you are developing applciation for both you have to use windows specific functions, such as:
use wcscat instead of strcat, use wsprintf instead of sprintf. There is windows specific alternate available for almost every string manipulatin function in windows. A full list of Win32 Equivalents for C Run-Time Functions is available at the end of this document.

2.Now problem is when you pass a string variable to this _T() macro, it gives a compiler error, such as:

TCHAR myStrVar;
MessageBox(NULL,_T(myStrVar),_T(myStrVar),0);

Solution is: Simply do not use _T() when passing variable instead of constant character string, as:

TCHAR myStrVar;
MessageBox(NULL,myStrVar,myStrVar,0);

Win32 Equivalents for C Run-Time Functions

Directly copied from Microsoft Win32 Software Development Kit (SDK), versions 3.1, 3.5, 3.51, and 4.0 Manual
Please note the string BOLD text in following table

SUMMARY

Many of the C Run-time functions have direct equivalents in the Win32
application programming interface (API). This article lists the C Run-time
functions by category with their Win32 equivalents or the word "none" if no
equivalent exists.

MORE INFORMATION

NOTE: the functions that are followed by an asterisk (*) are part of the
16-bit C Run-time only. Functions that are unique to the 32-bit C Run-time
are listed separately in the last section. All other functions are common
to both C Run-times.

Buffer Manipulation
-------------------
_memccpy none
memchr none
memcmp none
memcpy CopyMemory
_memicmp none
memmove MoveMemory

memset FillMemory, ZeroMemory
_swab none

Character Classification
------------------------
isalnum IsCharAlphaNumeric
isalpha IsCharAlpha, GetStringTypeW (Unicode)
__isascii none
iscntrl none, GetStringTypeW (Unicode)
__iscsym none
__iscsymf none
isdigit none, GetStringTypeW (Unicode)

isgraph none
islower IsCharLower, GetStringTypeW (Unicode)
isprint none
ispunct none, GetStringTypeW (Unicode)
isspace none, GetStringTypeW (Unicode)
isupper IsCharUpper, GetStringTypeW (Unicode)
isxdigit none, GetStringTypeW (Unicode)
__toascii none
tolower CharLower
_tolower none

toupper CharUpper
_toupper none

Directory Control
-----------------
_chdir SetCurrentDirectory
_chdrive SetCurrentDirectory
_getcwd GetCurrentDirectory
_getdrive GetCurrentDirectory
_mkdir CreateDirectory
_rmdir RemoveDirectory
_searchenv SearchPath

File Handling
-------------

_access none
_chmod SetFileAttributes
_chsize SetEndOfFile
_filelength GetFileSize
_fstat See Note 5
_fullpath GetFullPathName
_get_osfhandle none
_isatty GetFileType
_locking LockFileEx
_makepath none
_mktemp GetTempFileName
_open_osfhandle none

remove DeleteFile
rename MoveFile
_setmode none
_splitpath none
_stat none
_umask none
_unlink DeleteFile

Creating Text Output Routines
-----------------------------
_displaycursor* SetConsoleCursorInfo
_gettextcolor* GetConsoleScreenBufferInfo
_gettextcursor* GetConsoleCursorInfo

_gettextposition* GetConsoleScreenBufferInfo
_gettextwindow* GetConsoleWindowInfo
_outtext* WriteConsole
_scrolltextwindow* ScrollConsoleScreenBuffer
_settextcolor* SetConsoleTextAttribute
_settextcursor* SetConsoleCursorInfo
_settextposition* SetConsoleCursorPosition
_settextwindow* SetConsoleWindowInfo
_wrapon* SetConsoleMode

Stream Routines

---------------
clearerr none
fclose CloseHandle
_fcloseall none
_fdopen none
feof none
ferror none
fflush FlushFileBuffers
fgetc none
_fgetchar none
fgetpos none
fgets none
_fileno none
_flushall none

fopen CreateFile
fprintf none
fputc none
_fputchar none
fputs none
fread ReadFile
freopen (std handles) SetStdHandle
fscanf none
fseek SetFilePointer
fsetpos SetFilePointer
_fsopen CreateFile
ftell SetFilePointer (check return value)

fwrite WriteFile
getc none
getchar none
gets none
_getw none
printf none
putc none
putchar none
puts none
_putw none
rewind SetFilePointer
_rmtmp none
scanf none
setbuf none

setvbuf none
_snprintf none
sprintf wsprintf
sscanf none
_tempnam GetTempFileName
tmpfile none
tmpnam GetTempFileName
ungetc none
vfprintf none
vprintf none
_vsnprintf none
vsprintf wvsprintf

Low-Level I/O
-------------

_close _lclose, CloseHandle
_commit FlushFileBuffers
_creat _lcreat, CreateFile
_dup DuplicateHandle
_dup2 none
_eof none
_lseek _llseek, SetFilePointer
_open _lopen, CreateFile
_read _lread, ReadFile
_sopen CreateFile
_tell SetFilePointer (check return value)

_write _lread

Console and Port I/O Routines
-----------------------------
_cgets none
_cprintf none
_cputs none
_cscanf none
_getch ReadConsoleInput
_getche ReadConsoleInput
_inp none
_inpw none
_kbhit PeekConsoleInput
_outp none

_outpw none
_putch WriteConsoleInput
_ungetch none

Memory Allocation
-----------------
_alloca none
_bfreeseg* none
_bheapseg* none
calloc GlobalAlloc
_expand none
free GlobalFree
_freect* GlobalMemoryStatus
_halloc* GlobalAlloc
_heapadd none

_heapchk none
_heapmin none
_heapset none
_heapwalk none
_hfree* GlobalFree
malloc GlobalAlloc
_memavl GlobalMemoryStatus
_memmax GlobalMemoryStatus
_msize* GlobalSize
realloc GlobalReAlloc
_set_new_handler none
_set_hnew_handler* none
_stackavail* none

Process and Environment Control Routines
----------------------------------------
abort none
assert none
atexit none
_cexit none
_c_exit none
_exec functions none
exit ExitProcess
_exit ExitProcess
getenv GetEnvironmentVariable
_getpid GetCurrentProcessId

longjmp none
_onexit none
perror FormatMessage
_putenv SetEnvironmentVariable
raise RaiseException
setjmp none
signal (ctrl-c only) SetConsoleCtrlHandler
_spawn functions CreateProcess
system CreateProcess

String Manipulation

-------------------
strcat, wcscat lstrcat
strchr, wcschr none

strcmp, wcscmp lstrcmp
strcpy, wcscpy lstrcpy
strcspn, wcscspn none
_strdup, _wcsdup none
strerror FormatMessage
_strerror FormatMessage
_stricmp, _wcsicmp lstrcmpi
strlen, wcslen lstrlen
_strlwr, _wcslwr CharLower, CharLowerBuffer
strncat, wcsncat none
strncmp, wcsncmp none
strncpy, wcsncpy none
_strnicmp, _wcsnicmp none

_strnset, _wcsnset FillMemory, ZeroMemory
strpbrk, wcspbrk none
strrchr, wcsrchr none
_strrev, _wcsrev none
_strset, _wcsset FillMemory, ZeroMemory
strspn, wcsspn none
strstr, wcsstr none
strtok, wcstok none
_strupr, _wcsupr CharUpper, CharUpperBuffer

MS-DOS Interface
----------------
_bdos* none
_chain_intr* none

_disable* none
_dos_allocmem* GlobalAlloc
_dos_close* CloseHandle
_dos_commit* FlushFileBuffers
_dos_creat* CreateFile
_dos_creatnew* CreateFile
_dos_findfirst* FindFirstFile
_dos_findnext* FindNextFile
_dos_freemem* GlobalFree
_dos_getdate* GetSystemTime
_dos_getdiskfree* GetDiskFreeSpace
_dos_getdrive* GetCurrentDirectory

_dos_getfileattr* GetFileAttributes
_dos_getftime* GetFileTime
_dos_gettime* GetSystemTime
_dos_getvect* none
_dos_keep* none
_dos_open* OpenFile
_dos_read* ReadFile
_dos_setblock* GlobalReAlloc
_dos_setdate* SetSystemTime
_dos_setdrive* SetCurrentDirectory
_dos_setfileattr* SetFileAttributes
_dos_setftime* SetFileTime

_dos_settime* SetSystemTime
_dos_setvect* none
_dos_write* WriteFile
_dosexterr* GetLastError
_enable* none
_FP_OFF* none
_FP_SEG* none
_harderr* See Note 1
_hardresume* See Note 1
_hardretn* See Note 1
_int86* none
_int86x* none
_intdos* none

_intdosx* none
_segread* none

Time
----
asctime See Note 2
clock See Note 2
ctime See Note 2
difftime See Note 2
_ftime See Note 2
_getsystime GetLocalTime
gmtime See Note 2
localtime See Note 2
mktime See Note 2
_strdate See Note 2

_strtime See Note 2
time See Note 2
_tzset See Note 2
_utime SetFileTime

Virtual Memory Allocation
-------------------------
_vfree* See Note 3
_vheapinit* See Note 3
_vheapterm* See Note 3
_vload* See Note 3
_vlock* See Note 3
_vlockcnt* See Note 3
_vmalloc* See Note 3

_vmsize* See Note 3
_vrealloc* See Note 3
_vunlock* See Note 3

32-Bit C Run Time
------------------
_beginthread CreateThread
_cwait WaitForSingleObject w/ GetExitCodeProcess
_endthread ExitThread
_findclose FindClose
_findfirst FindFirstFile
_findnext FindNextFile
_futime SetFileTime

_get_osfhandle none
_open_osfhandle none
_pclose See Note 4
_pipe CreatePipe
_popen See Note 4

NOTE 1: The _harderr functions do not exist in the Win32 API. However, much
of their functionality is available through structured exception handling.

NOTE 2: The time functions are based on a format that is not used in Win32.
There are specific Win32 time functions that are documented in the Help

file.

NOTE 3: The virtual memory functions listed in this document are specific
to the MS-DOS environment and were written to access memory beyond the 640K
of RAM available in MS-DOS. Because this limitation does not exist in
Win32, the standard memory allocation functions should be used.

NOTE 4: While _pclose() and _popen() do not have direct Win32 equivalents,
you can (with some work) simulate them with the following calls:

_popen CreatePipe

CreateProcess

_pclose WaitForSingleObject
CloseHandle

NOTE 5: GetFileInformationByHandle() is the Win32 equivalent for the
_fstat() C Run-time function. However, GetFileInformationByHandle() is not
supported by Win32s version 1.1. It is supported in Win32s 1.2.
GetFileSize(), GetFileAttributes(), GetFileTime(), and GetFileTitle() are
supported by Win32s 1.1 and 1.2.

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