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Title: microsoft and unix specific and ISO c data types (int, size_t...
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C data types

general C datatypes
unix specific datatypes
ms_specific

general C data types

unsigned int: same as 'unsigned char', holds then +-127
short:
double:
float
: 64 bit
volatile: used to specify that a variable can be modified outside of main.

A char      is 1 bytes
An int      is 4 bytes
A short     is 2 bytes
A long      is 4 bytes
An unsigned char  is 1 bytes
An unsigned int   is 4 bytes
An unsigned short is 2 bytes
An unsigned long  is 4 bytes
A float     is 4 bytes
A double    is 8 bytes

strings
bstr: a length-prefixed string. _bstr_t lpctstr lpstr _T (a string precessor, which casts the string) lpcwstr lpwstr: in 32-bit type libraries Unicode strings can be defined with the LPWSTR data type. lpstr: indicates a zero-terminated string olechar

BSTR

A length-prefixed string used by Automation data manipulation functions. It has been described both as typedef OLECHAR *BSTR; and typedef LPWSTR. It is just a LPWSTR with the string length prefixed onto the string, taking up the first ULONG bytes.

BSTRs are wide, double-byte (Unicode) strings on 32-bit Windows

You create a string with SysAllocString.

And you release it with SysFreeString.

to get the length of a BSTR pass it to SysStringLen.

you changes the BSTR with SysReAllocString().

There are no functions to manipulate a sub-string within a BSTR...

compare javascript:

subst('Quiet lulls the peaceful mind', 'l', 'XX')

Results:Quiet XXuXXXXs the peacefuXX mind

subst('Quiet lulls the peaceful mind', 'l', 'll')

Results:Quiet llulllls the peacefull mind

substring( aStartIndex, anEndIndex)

Returns the characters found between the start and end indices, e.g., "Hello World".substring(0,1) returns "H". "Hello World".substring(4,10) returns "o Worl".

string1 + string2

Creates a new string which appends string1 with string2, e.g., "Hello "+"World" returns "Hello World"

compare VB:

Convert the code to a MFC CString or an STL basic_string<> and then use a SysReAllocString().

bstr_t

_bstr_t( char* s2 )

Constructs a _bstr_t object by calling SysAllocString to create a new BSTR object and encapsulate it. This constructor first performs a multibyte to Unicode conversion.

lpctstr

An LPCWSTR if UNICODE is defined, an LPCSTR otherwise. In other words, it is a pointer to a constant generic string.

lpcwstr

a constant for a lpcwstr.

lpstr

Pointer to a constant null-terminated string of 8-bit Windows (ANSI) characters.

lpwstr

Pointer to a constant null-terminated string of 16-bit Unicode characters.

VARIANT

A varaint is a union.

see the union how-to file in the howto/c/unions.htm directory . Books always document this data type. A Variant is based on the union type. The CComVariant type is an encapsulation of the three necessary steps in creating and using a VARIANT type.

atl data types

CComVariant
CComBSTR
SAFEARRAY

CComBSTR


CComBSTR();

CComBSTR(int nSize);

CComBSTR(int nSize, LPCOLESTR sz);

CComBSTR(LPCOLESTR psrc);

CComBSTR(const CComBSTR& src);

CComBSTR(REFGUID src); /*converts a GUID to a BSTR */

SAFEARRAY

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