| Description |
The FilePos function returns the current position in an open file. The returned value is the Record position, starting at 0 for the file beginning.
The file may be an Untyped, Typed or Text file.
The record length is as follows:
| Untyped files | : As set in Reset or ReWrite |
| Typed files | : SizeOf the file type |
| Text files | : Variable - defined by line ends |
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| Notes |
Seek to the given record position only works for binary files.
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| Related commands |
| Eoln |
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Returns true if the current text file is pointing at a line end |
| File |
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Defines a typed or untyped file |
| Seek |
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Move the pointer in a binary file to a new record position |
| SeekEoln |
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Skip to the end of the current line or file |
| TextFile |
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Declares a file type for storing lines of text |
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| Example code : Show the file position in a binary file |
// Full Unit code.
// -----------------------------------------------------------
// You must store this code in a unit called Unit1 with a form
// called Form1 that has an OnCreate event called FormCreate.
unit Unit1;
interface
uses
// The System unit does not need to be defined
SysUtils,
Forms, Dialogs;
type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm} // Include form definitions
procedure TForm1.FormCreate(Sender: TObject);
var
myWord, myWord1, myWord2, myWord3 : Word;
myFile : File of Word;
begin
// Try to open the Test.cus binary file in write only mode
AssignFile(myFile, 'Test.cus');
ReWrite(myFile);
// Write a few lines of Word data to the file
myWord1 := 123;
myWord2 := 456;
myWord3 := 789;
Write(myFile, myWord1, myWord2, myWord3);
// Close the file
CloseFile(myFile);
// Reopen the file in read only mode
FileMode := fmOpenRead;
Reset(myFile);
// Display the file contents
while not Eof(myFile) do
begin
Read(myFile, myWord);
// Note - FilePos shows the after read position
ShowMessage('Record '+
IntToStr(FilePos(myFile))+' = '+
IntToStr(myWord));
end;
// Close the file for the last time
CloseFile(myFile);
end;
end.
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| Hide full unit code |
Record 1 = 123
Record 2 = 456
Record 3 = 789
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