functions.pas

邮件系统的代码

unit Functions;

interface

uses
  Windows, SysUtils, DateUtils, ShlObj, ActiveX, ComObj, Registry;

const
  C1: Integer = 38784345; //初始化加解密钥的两个因子
  C2: Integer = 7342294;
  BaseTable = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='; //这是Base64转换用的常量字符

function getuserid: string; //得到一个用户的在线20位ID识别号(string)
function Replacing(S, source, target: string; times: Integer): string; //替换指定的字符串(源串，被换的串，换成为，多少次[-1--所有])
function DeleteSubString(S, substring: string; Times: Integer; CaseSensivte: Boolean): string; //删除指定字串，Times:指定次数[-1--所有],CaseSensivte:大小写是否敏感
function EncodeBase64(Source:string):string;
function DecodeBase64(Source:string):string;
function GetFileSize(filename:string):integer; //用findfrist方法得到一个文件的大小

implementation


function getuserid: string;
begin
  Randomize;
  result := formatdatetime('mmddhhnnsszzz', now) + FormatFloat('0000000', Random(9999999));
end;

function Replacing(S, Source, Target: string; Times: Integer): string;
var
  Site, StrLen, i: integer;
begin
  if Source <> Target then
  begin
    {source在S中出现的位置}
    StrLen := Length(Source);
    {source的长度}
    Site := Pos(Source, S);
    i := Times;
    while Site >= 1 do
    begin
      {删除source字符串}
      Delete(S, Site, StrLen);
      {插入target字符串到S中}
      Insert(Target, S, Site);
      {返回新串}
      Site := Pos(Source, s);
      dec(i);
      if i = 0 then
        break;
    end;
  end;
  Result := S;
end;

function DeleteSubString(S, substring: string; Times: Integer; CaseSensivte: Boolean): string;
var
  CharPos, l, i: Integer;
begin
  l := Length(SubString);
  if CaseSensivte then
    CharPos := Pos(SubString, S)
  else
    CharPos := Pos(UpperCase(SubString), UpperCase(S));
  i := Times;
  while CharPos > 0 do
  begin
    Delete(S, CharPos, l);
    dec(i);
    if i = 0 then
      break;
    if CaseSensivte then
      CharPos := Pos(SubString, S)
    else
      CharPos := Pos(UpperCase(SubString), UpperCase(S));
  end;
  Result := S;
end;

function EncodeBase64(Source:string):string;
var
  Times, LenSrc, i: Integer;
  x1, x2, x3, x4: Char;
  xt: Byte;
begin
  Result := '';
  LenSrc := Length(Source);
  if LenSrc mod 3 = 0 then
    Times := LenSrc div 3
  else
    Times := LenSrc div 3 + 1;
  for i := 0 to Times - 1 do
  begin
    if LenSrc >= (3 + i * 3) then
    begin
      x1 := BaseTable[(ord(Source[1 + i * 3]) shr 2)+1];
      xt := (ord(Source[1 + i * 3]) shl 4) and 48;
      xt := xt or (ord(Source[2 + i * 3]) shr 4);
      x2 := BaseTable[xt + 1];
      xt := (Ord(Source[2 + i * 3]) shl 2) and 60;
      xt := xt or (Ord(Source[3 + i * 3]) shr 6);
      x3 := BaseTable[xt + 1];
      xt := (ord(Source[3 + i * 3]) and 63);
      x4 := BaseTable[xt + 1];
    end
    else if LenSrc >= (2 + i * 3) then
    begin
      x1 := BaseTable[(Ord(Source[1 + i * 3]) shr 2) + 1];
      xt := (Ord(Source[1 + i * 3]) shl 4) and 48;
      xt := xt or (Ord(Source[2 + i * 3]) shr 4);
      x2 := BaseTable[xt + 1];
      xt := (Ord(Source[2 + i * 3]) shl 2) and 60;
      x3 := BaseTable[xt + 1];
      x4 := '=';
    end else
    begin
      x1 := BaseTable[(Ord(Source[1 + i * 3]) shr 2)+1];
      xt := (Ord(Source[1 + i * 3]) shl 4) and 48;
      x2 := BaseTable[xt + 1];
      x3 := '=';
      x4 := '=';
    end;
    Result := Result + x1 + x2 + x3 + x4;
  end;
end;

function DecodeBase64(Source:string):string;
var
  SrcLen,Times,i:integer;
  x1,x2,x3,x4,xt:byte;
begin
  result:='';
  SrcLen:=Length(Source);
  Times:=SrcLen div 4;
  for i:=0 to Times-1 do
  begin
    x1:=Pos(Source[1+i*4],BaseTable)-1;
    x2:=Pos(Source[2+i*4],BaseTable)-1;
    x3:=Pos(Source[3+i*4],BaseTable)-1;
    x4:=Pos(Source[4+i*4],BaseTable)-1;
    x1:=x1 shl 2;
    xt:=x2 shr 4;
    x1:=x1 or xt;
    x2:=x2 shl 4;
    result:=result+chr(x1);
    if x3= 64 then break;
    xt:=x3 shr 2;
    x2:=x2 or xt;
    x3:=x3 shl 6;
    result:=result+chr(x2);
    if x4=64 then break;
    x3:=x3 or x4;
    result:=result+chr(x3);
  end;
end;

function GetFileSize(filename:string):integer; //用findfrist方法得到一个文件的大小
var
  sr: TSearchRec;
begin
result:=0;
if FindFirst(filename, faAnyFile-faDirectory, sr) = 0 then
result:=sr.Size;
end;
end.