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Types

The following integer types are defined in the System unit: 
 Shortint = -128..127;
 SmallInt = -32768..32767;
 Longint  = $80000000..$7fffffff;
 byte     = 0..255;
 word     = 0..65535;
 dword    = longword;
 cardinal = longword;
 Integer  = smallint;
The following types are used for the functions that need compiler magic such as Val (588) or Str (580): 
 StrLenInt = LongInt;
 ValSInt = Longint;
 ValUInt = Cardinal;
 ValReal = Extended;
The Real48 type is defined to emulate the old Turbo Pascal Real type: 
 Real48 = Array[0..5] of byte;
The assignment operator has been overloaded so this type can be assigned to the Free Pascal native Double and Extended types. Real2Double (554).

The following character types are defined for Delphi compatibility: 

 TAnsiChar   = Char;
 AnsiChar    = TAnsiChar;
And the following pointer types as well: 
   PChar = ^char;
   pPChar = ^PChar;
   PAnsiChar   = PChar;
   PQWord      = ^QWord;
   PInt64      = ^Int64;
   pshortstring = ^shortstring;
   plongstring  = ^longstring;
   pansistring  = ^ansistring;
   pwidestring  = ^widestring;
   pextended    = ^extended;
   ppointer     = ^pointer;
For the SetJmp (569) and LongJmp (530) calls, the following jump bufer type is defined (for the I386 processor): 
   jmp_buf = record
     ebx,esi,edi : Longint;
     bp,sp,pc : Pointer;
     end;
   PJmp_buf = ^jmp_buf;
The following records and pointers can be used to scan the entries in the string message handler tables: 
   tmsgstrtable = record
      name : pshortstring;
      method : pointer;
   end;
   pmsgstrtable = ^tmsgstrtable;
 
   tstringmessagetable = record
      count : dword;
      msgstrtable : array[0..0] of tmsgstrtable;
   end;
   pstringmessagetable = ^tstringmessagetable;

The base class for all classes is defined as: 

 Type
   TObject = Class
   Public
     constructor create;
     destructor destroy;virtual;
     class function newinstance : tobject;virtual;
     procedure freeinstance;virtual;
     function safecallexception(exceptobject : tobject;
       exceptaddr : pointer) : longint;virtual;
     procedure defaulthandler(var message);virtual;
     procedure free;
     class function initinstance(instance : pointer) : tobject;
     procedure cleanupinstance;
     function classtype : tclass;
     class function classinfo : pointer;
     class function classname : shortstring;
     class function classnameis(const name : string) : boolean;
     class function classparent : tclass;
     class function instancesize : longint;
     class function inheritsfrom(aclass : tclass) : boolean;
     class function inheritsfrom(aclass : tclass) : boolean;
     class function stringmessagetable : pstringmessagetable;
     procedure dispatch(var message);
     procedure dispatchstr(var message);
     class function methodaddress(const name : shortstring) : pointer;
     class function methodname(address : pointer) : shortstring;
     function fieldaddress(const name : shortstring) : pointer;
     procedure AfterConstruction;virtual;
     procedure BeforeDestruction;virtual;
     procedure DefaultHandlerStr(var message);virtual;
   end;
   TClass = Class Of TObject;
   PClass = ^TClass;
Unhandled exceptions can be treated using a constant of the TExceptProc type: 
 TExceptProc = Procedure (Obj : TObject; Addr,Frame: Pointer);
Obj is the exception object that was used to raise the exception, Addr and Frame contain the exact address and stack frame where the exception was raised.

The TVarRec type is used to access the elements passed in a Array of Const argument to a function or procedure: 

 Type
   PVarRec = ^TVarRec;
   TVarRec = record
     case VType : Longint of
     vtInteger    : (VInteger: Longint);
     vtBoolean    : (VBoolean: Boolean);
     vtChar       : (VChar: Char);
     vtExtended   : (VExtended: PExtended);
     vtString     : (VString: PShortString);
     vtPointer    : (VPointer: Pointer);
     vtPChar      : (VPChar: PChar);
     vtObject     : (VObject: TObject);
     vtClass      : (VClass: TClass);
     vtAnsiString : (VAnsiString: Pointer);
     vtWideString : (VWideString: Pointer);
     vtInt64      : (VInt64: PInt64);
   end;
The heap manager uses the TMemoryManager type: 
   PMemoryManager = ^TMemoryManager;
   TMemoryManager = record
     Getmem      : Function(Size:Longint):Pointer;
     Freemem     : Function(var p:pointer):Longint;
     FreememSize : Function(var p:pointer;Size:Longint):Longint;
     AllocMem    : Function(Size:longint):Pointer;
     ReAllocMem  : Function(var p:pointer;Size:longint):Pointer;
     MemSize     : function(p:pointer):Longint;
     MemAvail    : Function:Longint;
     MaxAvail    : Function:Longint;
     HeapSize    : Function:Longint;
   end;
More information on using this record can be found in Programmers guide.

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