1.类型说明

Byte:Represents an 8-bit unsigned integer type.

[PByte:Is a pointer to a Byte.]

Char:Represents a word-sized (16-bits) character type

AnsiChar:Represents a byte-sized (8-bits) character type

WideChar：Represents a word-sized (16-bits) character type.

[PChar：Defines a null-terminated string]

[PAnsiChar：Defines a null-terminated ANSI string.]

String：Represents an alias for the generic UnicodeString type.

AnsiString：Represents a dynamically allocated string whose maximum length is limited only by available memory.

WideString：A null-terminated string of wide characters, with no reference counting.

[PString：Is a pointer to a String.]

[PAnsiString：Is a pointer to an AnsiString.]

TBytes：declares an array of Bytes.

2.指针

 1         var

 2           X, Y: Integer;  // X and Y are Integer variables

 3           P: ^Integer;     // P points to an Integer

 4         begin

 5           X := 17;      // assign a value to X

 6           P := @X;      // assign the address of X to P

 7           Y := P^;      // dereference P; assign the result to Y

 8         end;

type

  PInteger = ^Integer;

var

  R: Single;

  I: Integer;

  P: Pointer;

  PI: PInteger;

begin

  ...

  P := @R;

  PI := PInteger(P);

  I := PI^;

end;

3.一些点

SizeOf：Returns the number of bytes occupied by a variable or type.

Length：Returns the number of characters in a string or of elements in an array. 

Move：Copies bytes from a source to a destination. e.g.: Move(PChar(@arrBuf[0])^, LPChar^, aSectorNum * 512);

ByteLength：Returns the length of a given string in bytes.

GetBytes：Encodes a set of characters into a sequence of bytes

FillChar：Fills contiguous bytes with a specified value.

4.转换

TBytes -> PChar :     LPChar :=  PChar(LTBytes);

PChar -> TBytes：LTBytes := BytesOf(LPChar);

TBytes -> Array of AnsiChar：move(LTBytes[i],LArrayOfAnsiChar[k]);

Array of AnsiChar -> string：LString := StringOf(BytesOf(LArrayOfAnsiChar));