help-function.txt

DELPHI常用函数集及简要范例集

    ShowMessage('Good Morning')
  else
    ShowMessage('Good Afternoon');
end;
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Time				传回目前的时间.
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Unit		SysUtils
函数原型	function Time: TDateTime;
范例
procedure TForm1.Timer1Timer(Sender: TObject);
var
  DateTime : TDateTime;
  str : string;
begin
  DateTime := Time;  // store the current date and time
  str := TimeToStr(DateTime); // convert the time into a string
  Caption := str;  // display the time on the form's caption
  { Note This could have been done with the following line of code:
    Caption := TimeToStr(Time); }
end;
# Time, TimeToStr Example
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TimeToStr			时间转换成内定型字串.(09:20:15 PM)
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Unit		SysUtils
函数原型	function TimeToStr(Time: TDateTime): string;
 GetMem procedure		配置记忆体程序
New				配置指位器P的记忆体空间，
					大小为P所指型态的大小.
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Dispose			释放New所配置的记忆体.
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Unit		System
函数原型	procedure New(var P: Pointer);
函数原型	procedure Dispose(var P: Pointer);
范例		type
			  PListEntry = ^TListEntry;
			  TListEntry = record
 		  Next: PListEntry;
			  Text: string;
			  Count: Integer;
			end;
			var
			  List, P: PListEntry;
			begin
			  ...
			  New(P);
			  P^.Next := List;
			  P^.Text := 'Hello world';
			  P^.Count := 1;
			  List := P;
			  ...
			  Dispose(P);
			  …
			end;
范例
type
  Str18 = string[18];
 var
  P: ^Str18;
begin
  New(P);
  P^ := 'Now you see it...';
  Dispose(P);	{ Now you don't... }
end;
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GetMem			配置指位器P的记忆体空间，大小可自行设定.
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范例
var
  F: file;
  Size: Integer;
  Buffer: PChar;
begin
  AssignFile(F, 'test.txt');
  Reset(F, 1);
  try
    Size := FileSize(F);
    GetMem(Buffer, Size);
    try
      BlockRead(F, Buffer^, Size);
      ProcessFile(Buffer, Size);
    finally
      FreeMem(Buffer);
    end;
  finally
    CloseFile(F);
  end;
end;
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FreeMem			释放GetMem所配置的记忆体.
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Unit		System
函数原型	procedure GetMem(var P: Pointer; Size: Integer);
函数原型	procedure FreeMem(var P: Pointer[; Size: Integer]);
范例		var
			  F: file;
			  Size: Integer;
			  Buffer: PChar;
			begin
			  AssignFile(F, 'test.txt');
			  Reset(F, 1);
			  try
				Size := FileSize(F);
				GetMem(Buffer, Size);
				try
					BlockRead(F, Buffer^, Size);
					ProcessFile(Buffer, Size);
				finally
					FreeMem(Buffer);
 			end;
			  finally
				CloseFile(F);
			  end;
			end;

====================================
 File-management routines	档案管理常式
====================================
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ChangeFileExt	变更档案的副档名
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Unit		SysUtils
函数原型	function ChangeFileExt(const FileName, Extension: string): 
				string;
范例		procedure TForm1.Button1Click(Sender: TObject);
			var
			  S: String;
			  P1:String;
			  P2:String;
			begin
			  P1:='abc.txt';
			  P2:='.ini';
			  S := ChangeFileExt(P1,P2);
			  Label1.Caption:=S;
			end;

结果		S== 'abc.ini'

			P1:='abc'
			P2:='.ini'
			S== 'abc.ini'

			P1:='c:\windows\abc.txt'
			P2:='.ini'
			S=='c:\windows\abc.ini'

			P1:='abc.txt'
			P2:='ini'
			S=='abcini'
			**注意:P2的第一位元必须有一点'.ini'
范例
procedure TForm1.ConvertIcon2BitmapClick(Sender: TObject);

var 
  s : string;
  Icon: TIcon;
begin

  OpenDialog1.DefaultExt := '.ICO';

  OpenDialog1.Filter := 'icons (*.ico)|*.ICO';
  OpenDialog1.Options := [ofOverwritePrompt, ofFileMustExist, ofHideReadOnly ];
  if OpenDialog1.Execute then
  begin
    Icon := TIcon.Create;
    try
      Icon.Loadfromfile(OpenDialog1.FileName);
      s:= ChangeFileExt(OpenDialog1.FileName,'.BMP');
      Image1.Width := Icon.Width;
      Image1.Height := Icon.Height;
      Image1.Canvas.Draw(0,0,Icon);
      Image1.Picture.SaveToFile(s);

      ShowMessage(OpenDialog1.FileName + ' Saved to ' + s);
    finally
      Icon.Free;
    end;
  end;
end;
#  SaveToFile, Create, Height, Width, Canvas, ChangeFileExt example
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ExpandFileName	将档案名称加在目前所在之路径全名之後
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Unit		SysUtils
函数原型	function ExpandFileName(const FileName: string): string;
说明		设目前目录为	c:\windows\
			档案名称为		abc.txt
			则结果为		c:\windows\abc.txt
****		此函数并不是求abc.txt的所在路径.
范例		procedure TForm1.Button1Click(Sender: TObject);
			var
			  S: String;
			begin
			  S:=ExpandFileName('abc.txt');
			  Label1.Caption:=S;
			end;
范例
procedure TForm1.Button1Click(Sender: TObject)
begin
  ListBox1.Items.Add(ExpandFileName(Edit1.Text));
end;

------------------------------------------------------------------
DirectoryExists   目录是否存在------------------------------------------------------------------
Unit
FileCtrl

uses FileCtrl;

procedure TForm1.Button1Click(Sender: TObject);
begin
  if not DirectoryExists('c:\temp') then
    if not CreateDir('C:\temp') then
    raise Exception.Create('Cannot create c:\temp');
end;
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ForceDirectories    目录
---------------------------------------------------------
Unit    FileCtrl
函数原型     function ForceDirectories(Dir: string): Boolean;

procedure TForm1.Button1Click(Sender: TObject);
var
  Dir: string;
begin
  Dir := 'C:\APPS\SALES\LOCAL';
  if DirectoryExists(Dir) then
    Label1.Caption := Dir + ' was created'
end;
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ExpandUNCFileName	同上(只是得到网路上的路径)
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Unit		SysUtils
函数原型	function ExpandUNCFileName(const FileName: string):string;
ExtractFileDir 		分析字串中的路径
Unit	SysUtils
函数原型	function ExtractFileDir(const FileName: string): string;
说明		设S字串为	c:\windows\abc.txt
			则结果为	c:\windows
****		功能在於由任何部份传来的叁数,加以分析它的路径
范例		procedure TForm1.Button1Click(Sender: TObject);
			var
			  S: String;
			  P1:String;
			begin
			  P1:='c:\windows\abc.txt';
			  S:=ExtractFileDir(P1);
			  Label1.Caption:=S;
			end;

			S=='c:\windows'

			P1:='abc.txt'
			S==''

			P1:='c:abc.txt'
			S=='c:'

			P1:='c:\abc.txt'
			S=='c:\'
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ExtractFileDrive	分析字串中的磁碟机名称
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Unit		SysUtils
函数原型	function ExtractFileDrive(const FileName: string): string;
****		功能同上,只是传回磁碟机名称.
范例		procedure TForm1.Button1Click(Sender: TObject);
			var
			  S: String;
			  P1:String;
			begin
			  P1:='c:\windows\abc.txt';
			  S:=ExtractFileDrive(P1);
			  Label1.Caption:=S;
			end;

			S:='c:'

			P1:='abc.txt'
			S==''
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ExtractFileExt		分析字串中的档案名称的副档名
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Unit		SysUtils
函数原型	function ExtractFileExt(const FileName: string): string;
范例		procedure TForm1.Button1Click(Sender: TObject);
			var
			  S: String;
			  P1:String;
			begin
			  P1:='c:\windows\abc.txt';
			  S:=ExtractFileExt(P1);
			  Label1.Caption:=S;
			end;

			S=='.txt'

			P1:='c:\windows\abc'
			S==''
范例 MyFilesExtension := ExtractFileExt(MyFileName);
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ExtractFileName	分析字串中的档案名称(只传回档案名称)
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Unit		SysUtils
函数原型	function ExtractFileName(const FileName: string): string;
范例		procedure TForm1.Button1Click(Sender: TObject);
			var
			  S: String;
			  P1:String;
			begin
			  P1:='c:\windows\abc.txt';
			  S:=ExtractFileName(P1);
			  Label1.Caption:=S;
			end;

			S=='abc.txt'
范例
procedure TForm1.Button1Click(Sender: TObject);
var
  BackupName: string;
  FileHandle: Integer;
  StringLen: Integer;
  X: Integer;
  Y: Integer;
begin
  if SaveDialog1.Execute then
  begin
    if FileExists(SaveDialog1.FileName) then
    begin
      BackupName := ExtractFileName(SaveDialog1.FileName);
      BackupName := ChangeFileExt(BackupName, '.BAK');
      if not RenameFile(SaveDialog1.FileName, BackupName) then
        raise Exception.Create('Unable to create backup file.');
    end;
    FileHandle := FileCreate(SaveDialog1.FileName);
    { Write out the number of rows and columns in the grid. }
    FileWrite(FileHandle, 
      StringGrid1.ColCount, SizeOf(StringGrid1.ColCount));
    FileWrite(FileHandle, 
      StringGrid1.RowCount, SizeOf(StringGrid1.RowCount));
    for X := 0 to StringGrid1.ColCount ? 1 do
    begin
      for Y := 0 to StringGrid1.RowCount ? 1 do
      begin
        { Write out the length of each string, followed by the string itself. }
        StringLen := Length(StringGrid1.Cells[X,Y]);
        FileWrite(FileHandle, StringLen, SizeOf(StringLen));
        FileWrite(FileHandle,
          StringGrid1.Cells[X,Y], Length(StringGrid1.Cells[X,Y]);
      end;
    end;
    FileClose(FileHandle);
  end;
end;
##FileExists, RenameFile, FileCreate, FileWrite, FileClose, ExtractFileName Example
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ExtractFilePath	分析字串中的路径
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Unit		SysUtils
函数原型	function ExtractFilePath(const FileName: string): string;
说明		设S字串为	c:\windows\abc.txt
			则结果为	c:\windows\
范例		procedure TForm1.Button1Click(Sender: TObject);
			var
			  S: String;
			  P1:String;
			begin
			  P1:='c:\windows\abc.txt';
			  S:=ExtractFilePath(P1);
			  Label1.Caption:=S;
			end;
范例
begin
  with Session do
  begin
    ConfigMode := cmSession;
  try
    AddStandardAlias('TEMPDB', ExtractFilePath(ParamStr(0)), 'PARADOX');
  finally
      ConfigMode := cmAll;
  end;
end;
##ConfigMode, AddStandardAlias, ExtractFilePath example
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FileSearch			寻找档案在磁碟机中的正确路径
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Unit		SysUtils
函数原型	function FileSearch(const Name, DirList: string): string;
范例		var
			  s:string;
			begin
			  s:= FileSearch('abc.txt', 'c:\window\');
			  Label1.Caption:=s;
			end;
说明		找到传回c:\window\abc.txt	找不到传回空字串.
范例
procedure TForm1.Button1Click(Sender: TObject);
var
  buffer: array [0..255] of char;
  FileToFind: string;
begin
  GetWindowsDirectory(buffer, SizeOf(buffer));
  FileToFind := FileSearch(Edit1.Text, GetCurrentDir + ';' + buffer);
  if FileToFind = '' then
    ShowMessage('Couldn''t find ' + Edit1.Text + '.')
  else
    ShowMessage('Found ' + FileToFind + '.');
end;
##FileSearch, ShowMessage Example
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FileAge			传回档案的日期及时间(DOS型态).
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Unit		SysUtils
函数原型	function FileAge(const FileName: string): Integer;
说明		就是档案总管中档案内容裹面的修改日期.
范例		procedure TForm1.Button1Click(Sender: TObject);
			var