typed files
Typed file
A typed text file is suitable for processing files of any size. A typed text file consists of individual data records. All records in the file have the same structure. This means that each data record is of the same length.
Set the file and record structure
The structure applies to the file type and the record type. The file and data record must have the same structure.
type
TMemployee = Record
strName : String[20];
sinContent : Single;
end;Create the file
var
datFile : File of TMemployee;
recData : TMemployee;
begin
AssignFile(datFile, 'example.txt');
// An existing file is deleted and re-created
ReWrite(datFile);
...
end;Close the file
begin
...
Close(datFile); // closes the file
...
end;Write data record
var
datFile : File of TMemployee;
recData : TMemployee;
begin
...
// fill the record
recData.strName := 'abcdefghij';
recData.sinContent := 1700.21;
// write the record to the file
Write(datFile, recData);
...
end;Read data record
var
datFile : File of TMemployee;
recData : TMemployee;
begin
AssignFile(datFile, 'example.txt');
Reset(datFile); // Set the file pointer to the beginning of the file
Read(datFile, recData); // Reads a record from the file
...
end;Read file completely
var
datFile : File of TMemployee;
recData : TMemployee;
begin
AssignFile(datFile, 'example.txt');
Reset (datFile);
while not eof(datFile) // as long as data can still be read
do begin
read(datFile, recData); // read record from file
...
end;
CloseFile (datFile);
end;Position pointer on a data record
begin
AssignFile(datFile, 'example.txt');
Reset(datFile);
...
Seek(datFile, 0); // position file pointer at start of first record
Read(datFile, recData); // read first record into recData variable
recData.sinContent := 1602.22; // update record
Seek(datFile, 0); // position file pointer at start of first record
Write(datFile, recData); // write first record back
...
end;See also
From the Free Pascal wiki, page "typed files", as it stood on 2020-03-02 after a change by Trev, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's Licensing page. If you have concerns about this material, message the admin.
Talk about this page
Nobody has opened a bench for this page yet. Sign in to open one.