DelphiBasics
ReallocMem
Procedure
Reallocate an existing block of storage System unit
 procedure ReallocMem ( var StoragePointer : Pointer; StorageSize : Integer ) ;
Description
The ReallocMem procedure changes the storage size of an existing block of storage.
 
The size may be smaller or bigger.
 
If smaller, then the existing storage is effectively truncated, the remainder being released.
 
If larger, the storage is extended. Or a new block is allocated if necessary. In either case, the existing storage block data is preserved, and the new part is unitialised.
Notes
Warning : use with caution - excessive use can fragment storage.
Related commands
Dispose Dispose of storage used by a pointer type variable
FreeMem Free memory storage used by a variable
GetMem Get a specified number of storage bytes
New Create a new pointer type variable
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Example code : Allocate using GetMem and then reallocate using ReallocMem
type
  TRecord = Record
    name : string[10];
    age  : Byte;
  end;

var
  recPointer : ^TRecord;

begin
  // Allocate storage for 2 records
  // Note : It is better to use New for this
  // It is used here for illustration purposes only
  GetMem(recPointer, 2 * SizeOf(TRecord));

  // Fill out these 2 records with values
  recPointer.name := 'Brian';
  recPointer.age  := 23;

  Inc(recPointer);
  recPointer.name := 'Jim';
  recPointer.age  := 55;

  // Whoops - forgot to add Sally ...
  Dec(recPointer);
  ReallocMem(recPointer, 3 * SizeOf(TRecord));

  // Now add a third record
  Inc(recPointer,2);
  recPointer.name := 'Sally';
  recPointer.age  := 38;

  // Now display these values
  Dec(recPointer, 2);
  ShowMessageFmt('%s is %d',[recPointer.name, recPointer.age]);
  Inc(recPointer);
  ShowMessageFmt('%s is %d',[recPointer.name, recPointer.age]);
  Inc(recPointer);
  ShowMessageFmt('%s is %d',[recPointer.name, recPointer.age]);
end;
Show full unit code
   Brian is 23
   Jim is 55
   Sally is 38
 
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