delphi中无类型文件读写

Delphi代码


unit Unit1;

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, StdCtrls;

type

TForm1 = class(TForm)

Memo1: TMemo;

Button1: TButton;

Button2: TButton;

Button3: TButton;

Button4: TButton;

Button5: TButton;

Button6: TButton;

Button7: TButton;

procedure Button1Click(Sender: TObject);

procedure Button2Click(Sender: TObject);

procedure Button3Click(Sender: TObject);

procedure Button4Click(Sender: TObject);

procedure Button5Click(Sender: TObject);

procedure Button6Click(Sender: TObject);

procedure Button7Click(Sender: TObject);

private

{ Private declarations }

public

{ Public declarations }

end;

var

Form1: TForm1;

implementation

{$R *.dfm}

const

FileName = 'c:\temp\binary.dat';

var

F: file;

//用无类型的方式写入一个字节

procedure TForm1.Button1Click(Sender: TObject);

var

b: Byte;

begin

AssignFile(F,FileName);

Rewrite(F,1); //第二个参数表示: 把 1 个字节当作一个写入单位

b := 65;

BlockWrite(F,b,1); //写入; 参数2是要写入的内容; 参数3表示写入 1 次.

CloseFile(F);

//落实 binary.dat 的大小: 1个字节; 内容: A (可用记事本打开)

end;

//用无类型的方式读出一个字节

procedure TForm1.Button2Click(Sender: TObject);

var

b: Byte;

begin

AssignFile(F,FileName);

Reset(F,1); //把 1 个字节当作一个读取单位

BlockRead(F,b,1); //读取一次; 放入 b

ShowMessage(Chr(b)); //A

CloseFile(F);

end;

//写入更多字节

procedure TForm1.Button3Click(Sender: TObject);

var

buffer: array[0..127] of Byte;

i: Integer; //储存多个字节, 需要用数组了

begin

for i := Low(buffer) to High(buffer) do

buffer[i] := i; //给数组赋值, 注意现在数组大小是 128

AssignFile(F,FileName);

Rewrite(F,32); //规定把 32 个字节当作一个读取单位, 注意这个数字和缓冲区大小必须是倍数关系

BlockWrite(F,buffer,4); //需要写入几次呢? 128/32=4

CloseFile(F);

//写成的文件肯定是128字节大小, 但用记事本可能看不了, 因为这个二进制不是文本

end;

//读出

procedure TForm1.Button4Click(Sender: TObject);

var

buffer: array[0..127] of Byte;

i: Integer;

begin

AssignFile(F,FileName);

Reset(F,4); //把 4 字节当作一个读取单位; 为了那个倍数关系, 这里一般是 1

BlockRead(F,buffer,32); //当然需要 32 次才能读完

CloseFile(F);

//怎么显示一下呢? 还是用 Memo 吧; 显示字符? 数字? 还是十六进制吧

Memo1.Clear;

for i := Low(buffer) to High(buffer) do

begin

Memo1.Lines.Add(IntToHex(buffer[i],1));

end;

(*显示结果: 0 1 2 3 ... 7D 7E 7F *)

end;

//读写 Char 与实际读写字节

procedure TForm1.Button5Click(Sender: TObject);

var

cArr1,cArr2: array[0..4] of Char;

i: Integer;

num: Integer; //记录实际读写的字节数

begin

for i := Low(cArr1) to High(cArr1) do

cArr1[i] := Chr(65+i); //填充 A B C D E

AssignFile(F,FileName);

Rewrite(F,1); //建立

BlockWrite(F,cArr1,Length(cArr1),num); //参数4: num 是实际写入的字节数

ShowMessage(IntToStr(num)); //5

Reset(F,1); //重新打开

BlockRead(F,cArr2,Length(cArr2),num); //参数5: num 是实际读出的字节数

ShowMessage(IntToStr(num)); //5

ShowMessage(cArr2); //ABCDE

CloseFile(F);

end;

//写入长字符串, 读出其十六进制码

procedure TForm1.Button6Click(Sender: TObject);

var

p: PChar;

b: Byte;

begin

p := '万一的 Delphi 博客';

AssignFile(F,FileName); //关联文件名

Rewrite(F,1); //创建并打开

BlockWrite(F,p,Length(p)); //写入

FileMode := fmOpenRead; //这时可以设文件为只读

Reset(F,1); //为读取打开

Memo1.Clear;

while not Eof(F) do

begin

BlockRead(F,b,1);

Memo1.Text := Memo1.Text + IntToHex(b,2) + ' ';

end;

//显示结果: 70 F0 45 00 08 F7 12 00 A6 FB 43 00 A0 1A E5 00 FF C5

CloseFile(F);

end;

//复制个文件

procedure TForm1.Button7Click(Sender: TObject);

var

FromF,ToF: file;

NumRead,NumWritten: Integer;

Buffer: array[1..2048] of Byte;

begin

AssignFile(FromF, 'c:\temp\test1.dat'); //假定有这个文件

Reset(FromF, 1);

AssignFile(ToF, 'c:\temp\test2.dat');

Rewrite(ToF, 1);

repeat

BlockRead(FromF, Buffer, SizeOf(Buffer), NumRead);

BlockWrite(ToF, Buffer, NumRead, NumWritten);

until (NumRead = 0) or (NumWritten <> NumRead);

{ NumRead=0 表示读完了; NumWritten <> NumRead 表示磁盘空间不够了 }

CloseFile(FromF);

CloseFile(ToF);

end;

end.
http://peirenlei.iteye.com/blog/319562