delphi TFileStream流操作1

unit frmMain;

interface

uses

Winapi.Windows, Winapi.Messages, System.SysUtils,

System.Variants, System.Classes, Vcl.Graphics,

Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type

TForm1 = class(TForm)

Button1: TButton;

Button2: TButton;

Button3: TButton;

Button4: TButton;

Memo1: TMemo;

Button5: TButton;

procedure Button1Click(Sender: TObject);

procedure Button2Click(Sender: TObject);

procedure Button4Click(Sender: TObject);

procedure Button3Click(Sender: TObject);

procedure Button5Click(Sender: TObject);

private

{ Private declarations }

public

{ Public declarations }

end;

var

Form1: TForm1;

const

SOURCE_FILE_PATH: string = 'E:\Demo\a.txt';

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);

var

WriteFileStream, ReadFileStream: TFileStream;

begin

try

// 创建对象

ReadFileStream := TFileStream.Create('D:\常用软件下载.txt', fmOpenRead);

WriteFileStream := TFileStream.Create('E:\Demo\a.txt', fmCreate);

// 设置读取的位置

ReadFileStream.Position := 0;

WriteFileStream.CopyFrom(ReadFileStream, ReadFileStream.Size);

finally

FreeAndNil(ReadFileStream);

FreeAndNil(WriteFileStream);

end;

procedure TForm1.Button2Click(Sender: TObject);

var

FileStream: TFileStream;

var

Str: string;

var

StrByte: TBytes;

begin

// 字符串的长度、字符编码 Unicode、utf-8、gbk

Str := '期待B站粉丝破万';

try

FileStream := TFileStream.Create(SOURCE_FILE_PATH, fmCreate);

// 将string转换为指定编码的字节数组

StrByte := TEncoding.UTF8.GetBytes(Str);

FileStream.WriteBuffer(StrByte, Length(StrByte));

finally

FreeAndNil(FileStream);

end;

procedure TForm1.Button3Click(Sender: TObject);

var

FileStream: TFileStream;

var

Str: UTF8String;

begin

try

// 以只读的方式打开一个文件

FileStream := TFileStream.Create(SOURCE_FILE_PATH, fmOpenRead);

FileStream.Position := 0;

// 设置字符串的长度

SetLength(Str, FileStream.Size);

// 读取数据：解除指针引用，获取变量中的值

FileStream.Read(PChar(Str)^, FileStream.Size);

ShowMessage(Str);

finally

FreeAndNil(FileStream);

end;

procedure TForm1.Button4Click(Sender: TObject);

var

x: PInteger; // 整数类型的指针，指针就是一个存放内存地址的变量

y: Integer;

begin

y := 20;

x := @y;

ShowMessage(x^.ToString); // ^在变量名的右边时表示解除指针引用

end;

procedure TForm1.Button5Click(Sender: TObject);

var

FileStream: TFileStream;

var

Str: UTF8String;

begin

FileStream := TFileStream.Create(SOURCE_FILE_PATH, fmOpenRead);

FileStream.Position := 0;

SetLength(Str, FileStream.Size);

// 读取数据：解除指针引用，获取变量中的值

FileStream.Read(PChar(Str)^, FileStream.Size);

Self.Memo1.Lines.Add(Str);

FreeAndNil(FileStream);

end;

end.

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