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Views: 4361 | Replies: 2
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Join Date: Apr 2005
Posts: 10
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Newbie Poster
Passing txt files into a programand writeln info out Can anyone tell me the format for reading information into a program and if I want to save information out of the prgram into a txt file.
I understand it to be
Assign (file name, path)
reset (filename)
close (file name)
and to write information out
assign (filename, path);
rewrite(filename, with all the information)
close (filename)
Which brings up another question: Is it possible to read the txt file line by line and then save it out to another txt file line by line or must it be done as a entir file?
I understand it to be
Assign (file name, path)
reset (filename)
close (file name)
and to write information out
assign (filename, path);
rewrite(filename, with all the information)
close (filename)
Which brings up another question: Is it possible to read the txt file line by line and then save it out to another txt file line by line or must it be done as a entir file?
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Join Date: Jan 2005
Location: Georgia, USA
Posts: 8
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Solved Threads: 0
Newbie Poster
File I/O line-by-line (for text files) is fairly simple.
Assign associates an external filename with a file variable. This is the first step in file I/O. After the Assign, all references to the file are made through the file variable.
Reset opens a file for reading, preserving the contents and placing the file position at the beginning.
Rewrite opens a file for writing, destroying the contents and placing the file position at the beginning.
For Reset and Rewrite: If the file is an untyped file (i.e. F : file ), an optional record size parameter can be passed to the call (i.e. Reset( F, 256 )). Default record size is 128.
Append is used to open a text file, placing the file position at the end, to allow for the addition of text to the file.
File I/O with typed files is just about the same. Declare a file of a structured type (i.e. F : file of CustRec), then do a Reset. To get to record number N, call Seek( F, N ), where the first record in the file is record 0. In the case of file I/O on untyped files, Seek( F, N ) will seek N records into the file based on the filesize passed when the file was opened.
Be aware that some of this information may be specific to Delphi, but I believe it to be applicable to modern "generic" Pascal compilers. (For instance, Delphi now uses AssignFile to replace Assign, as Assign is now a method call in objects).
Assign associates an external filename with a file variable. This is the first step in file I/O. After the Assign, all references to the file are made through the file variable.
Reset opens a file for reading, preserving the contents and placing the file position at the beginning.
Rewrite opens a file for writing, destroying the contents and placing the file position at the beginning.
For Reset and Rewrite: If the file is an untyped file (i.e. F : file ), an optional record size parameter can be passed to the call (i.e. Reset( F, 256 )). Default record size is 128.
Append is used to open a text file, placing the file position at the end, to allow for the addition of text to the file.
File I/O with typed files is just about the same. Declare a file of a structured type (i.e. F : file of CustRec), then do a Reset. To get to record number N, call Seek( F, N ), where the first record in the file is record 0. In the case of file I/O on untyped files, Seek( F, N ) will seek N records into the file based on the filesize passed when the file was opened.
Be aware that some of this information may be specific to Delphi, but I believe it to be applicable to modern "generic" Pascal compilers. (For instance, Delphi now uses AssignFile to replace Assign, as Assign is now a method call in objects).
procedure CopyFile;
var
F1 : text;
F2 : text;
FN1 : string;
FN2 : string;
begin
FN1 := 'infile.txt';
FN2 := 'outfile.txt';
assign( F1, FN1 );
reset( F1 ); { open file for reading }
assign( F2, FN2 );
rewrite( F2 ); { open file for writing, destroying contents, if any }
while not EOF( F1 ) do
begin
readln( F1 );
{ file manipulation goes here }
writeln( F2 );
end;
close( F1 );
close( F2 );
end; |
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