Window中数据类型

Integer types

Data typeSizeSigned?BYTE8 bitsUnsignedDWORD32 bitsUnsignedINT3232 bitsSignedINT6464 bitsSignedLONG32 bitsSignedLONGLONG64 bitsSignedUINT3232 bitsUnsignedUINT6464 bitsUnsignedULONG32 bitsUnsignedULONGLONG64 bitsUnsignedWORD16 bitsUnsigned

Boolean Type

BOOL 这里是整形和C++中的bool不同

if (result)//正确

if(result==TRUE)//错误

Pointer Types

Windows defines many data types of the form pointer-to-X. These usually have the prefix P- or LP- in the name. For example, LPRECT is a pointer to a RECT, where RECT is a structure that describes a rectangle. The following variable declarations are equivalent.

Historically, P stands for "pointer" and LP stands for "long pointer". Long pointers (also called far pointers) are a holdover from 16-bit Windows, when they were needed to address memory ranges outside the current segment. The LP prefix was preserved to make it easier to port 16-bit code to 32-bit Windows. Today there is no distinction — a pointer is a pointer.

Pointer Precision Types

The following data types are always the size of a pointer — that is, 32 bits wide in 32-bit applications, and 64 bits wide in 64-bit applications. The size is determined at compile time. When a 32-bit application runs on 64-bit Windows, these data types are still 4 bytes wide. (A 64-bit application cannot run on 32-bit Windows, so the reverse situation does not occur.)

• DWORD_PTR
• INT_PTR
• LONG_PTR
• ULONG_PTR
• UINT_PTR

These types are used in situations where an integer might be cast to a pointer. They are also used to define variables for pointer arithmetic and to define loop counters that iterate over the full range of bytes in memory buffers. More generally, they appear in places where an existing 32-bit value was expanded to 64 bits on 64-bit Windows.

Hungarian Notation

匈牙利命名，类型+变量名

如DWORD 类型可以命名如下dwVar

WORD命名wVar

Strings

Windows natively supports Unicode strings for UI elements, file names, and so forth. Unicode is the preferred character encoding, because it supports all character sets and languages. Windows represents Unicode characters using UTF-16 encoding, in which each character is encoded as a 16-bit value. UTF-16 characters are called wide characters, to distinguish them from 8-bit ANSI characters. The Visual C++ compiler supports the built-in data typewchar_t for wide characters. The header file WinNT.h also defines the followingtypedef.

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typedef wchar_t WCHAR;

You will see both versions in MSDN example code. To declare a wide-character literal or a wide-character string literal, putL before the literal.

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wchar_t a = L'a';wchar_t *str = L"hello";

Here are some other string-related typedefs that you will see:

TypedefDefinitionCHARcharPSTR or LPSTRchar*PCSTR or LPCSTRconst char*PWSTR or LPWSTRwchar_t*PCWSTR or LPCWSTRconst wchar_t*

 

Unicode and ANSI Functions

When Microsoft introduced Unicode support to Windows, it eased the transition by providing two parallel sets of APIs, one for ANSI strings and the other for Unicode strings. For example, there are two functions to set the text of a window's title bar:

• SetWindowTextA takes an ANSI string.
• SetWindowTextW takes a Unicode string.

Internally, the ANSI version translates the string to Unicode. The Windows headers also define a macro that resolves to the Unicode version when the preprocessor symbolUNICODE is defined or the ANSI version otherwise.

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#ifdef UNICODE#define SetWindowText  SetWindowTextW#else#define SetWindowText  SetWindowTextA#endif 

In MSDN, the function is documented under the name SetWindowText, even though that is really the macro name, not the actual function name.

New applications should always call the Unicode versions. Many world languages require Unicode. If you use ANSI strings, it will be impossible to localize your application. The ANSI versions are also less efficient, because the operating system must convert the ANSI strings to Unicode at run time. Depending on your preference, you can call the Unicode functions explicitly, such asSetWindowTextW, or use the macros. The example code on MSDN typically calls the macros, but the two forms are exactly equivalent. Most newer APIs in Windows have just a Unicode version, with no corresponding ANSI version.

TCHARs

Back when applications needed to support both Windows NT as well as Windows 95, Windows 98, and Windows Me, it was useful to compile the same code for either ANSI or Unicode strings, depending on the target platform. To this end, the Windows SDK provides macros that map strings to Unicode or ANSI, depending on the platform.

MacroUnicodeANSITCHARwchar_tcharTEXT("x")L"x""x"

 

For example, the following code:

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SetWindowText(TEXT("My Application"));

resolves to one of the following:

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SetWindowTextW(L"My Application"); // Unicode function with wide-character string.SetWindowTextA("My Application");  // ANSI function.

The TEXT and TCHAR macros are less useful today, because all applications should use Unicode. However, you might see them in older code and in some of the MSDN code examples.

The headers for the Microsoft C run-time libraries define a similar set of macros. For example,_tcslen resolves to strlen if _UNICODE is undefined; otherwise it resolves towcslen, which is the wide-character version of strlen.

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#ifdef _UNICODE#define _tcslen     wcslen#else#define _tcslen     strlen#endif 

Be careful: Some headers use the preprocessor symbol UNICODE, others use_UNICODE with an underscore prefix. Always define both symbols. Visual C++ sets them both by default when you create a new project.