Windows programming - (b) Unicode Introduction

Wide and 2.2 C language

2.2.2 broader character

Wide character in the C language is based on short-type data, this data type is defined in the header file WCHAR.H is from:

typedef unsigned short wchar_t ;

Therefore wchar_t wide character data type with an unsigned short integer unsigned short C language, are 16 bits wide.

E.g:

wchar_t c = 'A' ;

Saved on your computer is 0x0041, appears as 0x41 0x00

2.2.3 Wide character library functions

When using a wide character length calculating strlen:

#include <stdio.h>
#include <string.h>

int main()
{
　　wchar_t *p = L"Hello" ;
　　printf( "%d\n", strlen(p) ) ;

　　return 0 ;
}

The results show that after 1 run is, obviously, it does not obtain the correct length, this is because the wide-character string "Hello" period value stored in the memory as follows:

48 00 65 00 6C 00 6C 00 6F 00 21 00

This is because when strlen find the first 0:00 of the string is considered that the string has ended, so the length was obtained as a 1, strlen to count this one is the 0x48 character represented 'H'.

We use wcslen wide character length calculating function. Same thing

Function name	Function prototype	Function Function	return value
wcscat	wchar_t wcscat(wchar_t s1, const wchar_t *s2);	The connection string s1 s2 referred to later	referring to the first address of the string s1
wcschr	wchar_t wcschr(const wchar_t s, wchar_t c);	Locate the first occurrence of the character c in the string s	If found, the address of the character is returned, otherwise NULL
wcscmp	int wcscmp(const wchar_t s1, const wchar_t s2);	Let the string s1 s2 compared with strings	s1 <s2, returns negative; s1 == s2, returns 0; s1> s2, returns a positive number
wcscpy	wchar_t wcscpy(wchar_t s1, const wchar_t *s2);	Copy the string referred s2 cover in s1	First address string referred s1
wcslen	size_t wcslen(const wchar_t *s);	S requirements referred string length	Returns the number of valid characters
wcsstr	wchar_t * wcsstr(const wchar_t s1, const wchar_t s2);	Find the position of the string in the string s1 s2 first occurrence	If found, the address of the location is returned, otherwise returns NULL

2.2.4 maintain a source code file

Use the TEXT avoid using L "hello" directly TEXT ( "hello")

TEXT retrospective definition of the place has been found that the addition of L

#define TEXT(quote) __TEXT(quote)   // r_winnt

#define __TEXT(quote) L##quote      // r_winnt

Therefore, use the TEXT or _TEXT can not thank the L

2.3 wide and Windows

Type 2.3.1 Windows header file

Windows program includes a header file WINDOWS.H. The document includes a number of other header files, including WINDEF.H, the file has a number of basic patterns used in Windows-defined, and it is itself also includes WINNT.H. WINNT.H handle basic Unicode support.

WINNT.H comprising front headers CTYPE.H table C, which is one of the many C header file, including the definition of wchar_t. WINNT.H defines a new data type, referred to as CHAR and WCHAR:

typedef char CHAR ;        
typedef wchar_t WCHAR ;    // wc

When you need to define eight characters or 16 characters, it is recommended that you use in Windows programs and data types are CHAR WCHAR. WCHAR Comment defined behind Hungarian notation is recommended: a variable based WCHAR data patterns may be attached in front of the letter to indicate a wide character wc.

Further WINNT.H header file defines a pointer to a string used as 8 and six data patterns used as four 8 const pointer to a string data type. Here a selection of header files some practical explanation data type statement:

typedef CHAR * PCHAR, * LPCH, * PCH, * NPSTR, * LPSTR, * PSTR ;        
typedef CONST CHAR * LPCCH, * PCCH, * LPCSTR, * PCSTR ;

N and L represents the prefix "near" and "long", referring to the 16-bit Windows in two sizes different indicators. Win32 no difference in the near and long index.

Similarly, WINNT.H defined as six 16-bit pointer to a string data type as const, and four 16-bit pointer to a string data type:

typedef WCHAR * PWCHAR, * LPWCH, * PWCH, * NWPSTR, * LPWSTR, * PWSTR ;        
typedef CONST WCHAR * LPCWCH, * PCWCH, * LPCWSTR, * PCWSTR ;

At this point, we have the data type CHAR (an 8-bit char) and WCHAR (a 16-bit wchar_t), and point to CHAR and WCHAR indicators. Like with TCHAR.H, WINNT.H TCHAR is defined as the general character type. If the UNICODE definition identifier (not the bottom line), and the TCHAR indicators pointing to TCHAR are defined as indicators of WCHAR and directed WCHAR; if the UNICODE identifier is not defined, and the point of TCHAR TCHAR index to point to, and are defined as char char indicators:

#ifdef  UNICODE 
typedef WCHAR TCHAR, * PTCHAR ;
typedef LPWSTR LPTCH, PTCH, PTSTR, LPTSTR ; 
typedef LPCWSTR LPCTSTR ;      
#else
typedef char TCHAR, * PTCHAR ;  
typedef LPSTR LPTCH, PTCH, PTSTR, LPTSTR ; 
typedef LPCSTR LPCTSTR ;   
#endif

If you have defined TCHAR data type in a header file, or other header file, then WINNT.H and WCHAR.H header file can be defined to prevent their repetition. However, whenever the use of other header files in the program, should be included before any other WINDOWS.H header file.

WINNT.H header file also defines a macro that added prior to the first L-quoted strings. If UNICODE is defined identifier, it is called a macro __TEXT defined as follows:

#define __TEXT(quote) L##quote

If not defined identifier UNICODE, like the definition of __TEXT macro:

#define __TEXT(quote) quote

Further, TEXT macro is thus defined:

#define TEXT(quote) __TEXT(quote)

This method TCHAR.H _TEXT macro defined in the same, but do not have to worry about the bottom line. I will use this macro TEXT version of the book.

These definitions allow you mix ASCII and Unicode strings in the same program, or may be written in a compiled program ASCII or Unicode. If you want to explicitly define the 8-bit character variables and strings, use CHAR, PCHAR (or other), as well as a quoted string. To explicitly use 16-bit character variables and strings, use WCHAR, PWCHAR, and L added to the front of the quotation mark. For 8-bit or 16-bit depending on the definition of a variable or an identifier UNICODE string to use TCHAR, PTCHAR and TEXT macro.

2.3.2 Windows function calls

MessageBoxA:

WINUSERAPI int WINAPI MessageBoxA (HWND hWnd, LPCSTR lpText, 
                           LPCSTR lpCaption, UINT uType) ;

Here is MessageBoxW:

WINUSERAPI int WINAPI MessageBoxW (HWND hWnd, LPCWSTR lpText,
        
                           LPCWSTR lpCaption, UINT uType) ;

Their second and third arguments are a string constant pointer

MessageBox will be called according to the parameter type:

#ifdef UNICODE
#define MessageBox  MessageBoxW
#else
#define MessageBox  MessageBoxA
#endif // !UNICODE

2.3.3 Windows string functions

The following is a set of string functions defined by Windows, these functions are used to calculate the length of the string, copy the string, the connection string and the comparison string:

ILength = lstrlen (pString); 
        
pString = lstrcpy (pString1, pString2); 
        
pString = lstrcpyn (pString1, pString2, iCount); 
        
pString = lstrcat (pString1, pString2); 
        
ICOMP = lstrcmp (pString1, pString2); 
        
ICOMP = lstrcmpi (pString1, pString2);

These functions are the same as the corresponding C function link library functions. If the UNICODE identifier is defined, then the function will accept wide strings, or only accept conventional strings. LstrlenW wide string version of the function may be performed in Windows 98.

2.3.4 Use printf in Windows

You can not use the printf function in Windows programs, but the use of other functions:

#include <Windows.h>
#include <stdio.h>
#include <stdlib.h>

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
    char szBuffer[100];
    sprintf(szBuffer, "The Sum of %i and %i is %i\n", 5, 3, 5 + 3);
    MessageBox(NULL, szBuffer, TEXT("Hk_Mayfly"), 0x4L | 0x40L);

    return 0;
}

The following table lists all the sprintf function Microsoft C run-time libraries and Windows support.

	ASCII	Wide character	conventional
The number of variable parameters
Standard Edition	sprintf	swprintf	_stprintf
The maximum length version	_snprintf	_snwprintf	_sntprintf
Windows version	wsprintfA	wsprintfW	wsprintf
Pointer parameter array
Standard Edition	vsprintf	vswprintf	_vstprintf
The maximum length version	_vsnprintf	_vsnwprintf	_vsntprintf
Windows version	wvsprintfA	wvsprintfW	wvsprintf

2.3.5 formatted message box

#include <windows.h>      
#include <tchar.h>          
#include <stdio.h>   
        
int CDECL MessageBoxPrintf (TCHAR * szCaption, TCHAR * szFormat, ...)
        
{
        
    TCHAR   szBuffer [1024] ;
        
    va_list pArgList ;
        

    // The va_start macro (defined in STDARG.H) is usually equivalent to:
        
    // pArgList = (char *) &szFormat + sizeof (szFormat) ;
        

    va_start (pArgList, szFormat) ;
        

    // The last argument to wvsprintf points to the arguments
        

    _vsntprintf ( szBuffer, sizeof (szBuffer) / sizeof (TCHAR),
        
                   szFormat, pArgList) ;
        

    // The va_end macro just zeroes out pArgList for no good reason
        
    va_end (pArgList) ;
        
    return MessageBox (NULL, szBuffer, szCaption, 0) ;
        
}
        
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
        
                   PSTR szCmdLine, int iCmdShow)
        
{
        
    int cxScreen, cyScreen ;
        
    cxScreen = GetSystemMetrics (SM_CXSCREEN) ;
        
    cyScreen = GetSystemMetrics (SM_CYSCREEN) ;
        

    MessageBoxPrintf (    TEXT ("ScrnSize"),
        
                   TEXT ("The screen is %i pixels wide by %i pixels high."),
        
                   cxScreen, cyScreen) ;
        
    return 0 ;
        
}