无类型文件读写
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.
