Non-type file read/write

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, stdctrls; Type tform1 = Class (tform) memo1: tmemo; button1: tbutton; handler: tbutton; button3: tbutton; button4: tbutton; button5: tbutton; button6: tbutton; button7: handler; Procedure destroy (Sender: tobject ); procedure button3click (Sender: TOB Ject); 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; // write a byte procedure tform1.button1click (Sender: tobject) in a non-typed manner; var B: Byte; begin assignfile (F, filename); rewrite (F, 1); // The second parameter indicates that 1 byte is treated as a write unit B: = 65; blockwrite (F, B, 1); // write; parameter 2 indicates the content to be written; parameter 3 indicates the write once. closefile (f); // implements binary. dat size: 1 byte; content: A (available in Notepad) end; // read a byte in non-typed mode procedure tform1.button2click (Sender: tobject); var B: byte; begin assignfile (F, filename); reset (F, 1); // treats one byte as a read unit blockread (F, B, 1 ); // read once; put B showmessage (CHR (B); // A closefile (f); End; // Write more bytes procedure tform1.button3click (Sender: tobject); var Buffer: array [0 .. 127] of byte; I: integer; // stores multiple bytes. you need to use an array of begin for I: = low (buffer) to high (buffer) Do buffer [I]: = I; // assign a value to the array. Note that the current array size is 128 assignfile (F, filename); rewrite (F, 32 ); // The 32 bytes are regarded as a read unit. Note that the number and the buffer size must be multiples of blockwrite (F, buffer, 4). // how many times does it need to be written? 128/32 = 4 closefile (f); // the size of the written file must be 128 bytes, but it may not be visible in notepad, because the binary is not the end of the text; // read procedure tform1.button4click (Sender: tobject); var Buffer: array [0 .. 127] of byte; I: integer; begin assignfile (F, filename); reset (F, 4); // 4 bytes are treated as a read unit; for that multiple relationship, here is generally 1 blockread (F, buffer, 32); // Of course, it takes 32 times to read closefile (f); // how can I display it? Or use memo to display characters? Number? Memo1.clear; for I: = low (buffer) to high (buffer) Do begin memo1.lines. add (inttohex (buffer [I], 1); end; (* display result: 0 1 2 3... 7D 7E 7f *) end; // read/write char and actual read/write bytes procedure tform1.button5click (Sender: tobject); var carr1, carr2: array [0 .. 4] of char; I: integer; num: integer; // records the actual number of bytes read and write. Begin for I: = low (carr1) to high (carr1) do carr1 [I]: = CHR (65 + I); // fill in a B c d e assignfile (F, filename); rewrite (F, 1 ); // create blockwrite (F, carr1, length (carr1), num); // parameter 4: num is the actual number of bytes written showmessage (inttostr (Num )); // 5 reset (F, 1); // re-open blockread (F, carr2, length (carr2), num); // parameter 5: num is the actual number of bytes read showmessage (inttostr (Num); // 5 showmessage (carr2); // ABCDE closefile (f); end; // write a long string, read its hexadecimal code procedure tform1.button6click (Sender: tobject); var P: pchar; B: byte; begin P: = 'in case of Delphi blog'; assignfile (F, filename); // associated file name rewrite (F, 1); // create and open blockwrite (F, P, length (p); // write filemode: = fmopenread; // you can set the file to read-only reset (F, 1); // open memo1.clear for reading; while not EOF (f) Do begin blockread (F, B, 1 ); memo1.text: = memo1.text + inttohex (B, 2) + ''; end; // display the result: 70 F0 45 00 08 F7 12 00 A6 FB 43 00 A0 1A E5 00 FF C5 closefile (f); end; // copy the procedure tform1.button7click (Sender: tobject) file ); vaR fromf, TOF: file; numread, numwritten: integer; Buffer: array [1 .. 2048] of byte; begin assignfile (fromf, 'c: \ temp \ test1.dat '); // assume that this file is 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 indicates that the read is finished; numwritten numread indicates that the disk space is insufficient} closefile (fromf); closefile (TOF); end; end.