3.4. Strings
In C, as in Delphi, a string is an array of char types. Often, a string declaration is used in combination with a constant declaration specifying the maximum string length, as the following example shows: #define RAS_MaxEntryName 256
#define RASENTRYNAMEA struct tagRASENTRYNAMEA
RASENTRYNAMEA
{
DWORD dwSize;
CHAR szEntryName[ RAS_MaxEntryName + 1 ];
};
The first line declares a constant RAS_MaxEntryName with the value 256 specifying the maximum length of the string. The lines after it declare a struct (record) which contains a null-terminated string: CHAR szEntryName[ RAS_MaxEntryName + 1 ];
The Delphi translation: szEntryName : Array [0..RAS_MaxEntryName] of Char;
Why not Array [0..RAS_MaxEntryName+1] of Char? Recall that a C array starts with 0 and the declaration specifies the number of elements. Thus, Array [0..RAS_MaxEntryName+1] in Delphi is equivalent to [RAS_MaxEntryName+2] in C.
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3.5. Enumerations - Two Methods
Enumerated types can be translated in two ways.
Method 1: typedef enum _FINDEX_INFO_LEVELS {
FindExInfoStandard,
FindExInfoMaxInfoLevel
} FINDEX_INFO_LEVELS;
This part of a C-header file translates easily to Delphi: Type
TFindExInfoLevels = (FindExInfoStandard,
FindExInfoMaxInfoLevel);
The ordinal Value of the item FindExInfoStandard is 0. In Delphi each enumeration starts with 0.
Method 2:
The following C-declaration is more problematic: typedef enum _ACL_INFORMATION_CLASS {
AclRevisionInformation = 1,
AclSizeInformation
} ACL_INFORMATION_CLASS
The "= 1" in the declaration forces C to start with the ordinal value 1. This is not possible in Delphi.
There are two ways to solve the problem.
Solution a): Declare the enumeration as TACLInformationClass = (_Fill0,
AclRevisionInformation,
AclSizeInformation);
Solution b): Translate the enumeration as CONST
AclRevisionInformation = 1;
AclSizeInformation = 2;
TYPE
TACLInformationClass = DWord;
That's no problem for this example. But in C it's possible to specify the ordinal value of each item of the enumeration, for example: Typedef enum _ENUMEXAMPLE {
Item1 = 5,
Item2 = 10,
} ENUMEXAMPLE;
Using enumeration in Delphi the declaration would have to be done like this: TEnumExample = (_Fill0,
_Fill1,
_Fill2,
_Fill3,
_Fill4,
Item1,
_Fill6,
_Fill7,
_Fill8,
_Fill9,
Item2);
This is hard to read and clumsy to maintain.
This works better:
CONST
Item1 = 5;
Item2 = 10;
TYPE
TEnumExample = DWord;
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