Difference between revisions of "TFileStream"
From Free Pascal wiki
Jump to navigationJump to searchm |
(Remove incorrect statement that TFileStream reads entire file. Avoid FreeAndNil of local variables.) |
||
| Line 1: | Line 1: | ||
{{TFileStream}} | {{TFileStream}} | ||
| − | A '''TFileStream''' is a descendant of [[TStream]] that gets/stores its data from/to a file on disk. | + | A '''TFileStream''' is a descendant of [[TStream]] that gets/stores its data from/to a file on disk. |
| − | |||
{| class="wikitable sortable" | {| class="wikitable sortable" | ||
! Constant !! Decimal !! Description | ! Constant !! Decimal !! Description | ||
| Line 27: | Line 26: | ||
|} | |} | ||
| − | read | + | * read entire file ''fnam'' to a string. |
<syntaxhighlight> | <syntaxhighlight> | ||
| − | function readstream( fnam: string ): string; | + | function readstream(fnam: string): string; |
var | var | ||
strm: TFileStream; | strm: TFileStream; | ||
| Line 36: | Line 35: | ||
begin | begin | ||
txt := ''; | txt := ''; | ||
| − | strm := TFileStream.Create( fnam, fmOpenRead or fmShareDenyWrite ); | + | strm := TFileStream.Create(fnam, fmOpenRead or fmShareDenyWrite); |
try | try | ||
n := strm.Size; | n := strm.Size; | ||
| − | SetLength( txt, n ); | + | SetLength(txt, n); |
| − | strm.Read( txt[1], n ); | + | strm.Read(txt[1], n); |
finally | finally | ||
| − | + | strm.Free; | |
end; | end; | ||
result := txt; | result := txt; | ||
| Line 48: | Line 47: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| − | Write ''txt'' to file ''fnam''. | + | * Write a string ''txt'' to file ''fnam''. |
<syntaxhighlight> | <syntaxhighlight> | ||
| − | procedure writestream( fnam: string; txt: string ); | + | procedure writestream(fnam: string; txt: string); |
var | var | ||
strm: TFileStream; | strm: TFileStream; | ||
n: longint; | n: longint; | ||
begin | begin | ||
| − | strm := TFileStream.Create( fnam, fmCreate ); | + | strm := TFileStream.Create(fnam, fmCreate); |
| − | n := Length( txt ); | + | n := Length(txt); |
try | try | ||
strm.Position := 0; | strm.Position := 0; | ||
| − | strm.Write( txt[1], n ); | + | strm.Write(txt[1], n); |
finally | finally | ||
| − | + | strm.Free; | |
end; | end; | ||
end; | end; | ||
Revision as of 10:26, 25 April 2018
│
Deutsch (de) │
English (en) │
français (fr) │
polski (pl) │
A TFileStream is a descendant of TStream that gets/stores its data from/to a file on disk.
| Constant | Decimal | Description |
|---|---|---|
| fmCreate | 65280 | Creates a new file |
| fmOpenRead | 0 | opens a file for reading |
| fmOpenWrite | 1 | opens a file for writing |
| fmOpenReadWrite | 2 | opens a file for reading and writing |
| fmShareDenyWrite | 32 | prohibit writing if file is already opened |
- read entire file fnam to a string.
function readstream(fnam: string): string;
var
strm: TFileStream;
n: longint;
txt: string;
begin
txt := '';
strm := TFileStream.Create(fnam, fmOpenRead or fmShareDenyWrite);
try
n := strm.Size;
SetLength(txt, n);
strm.Read(txt[1], n);
finally
strm.Free;
end;
result := txt;
end;- Write a string txt to file fnam.
procedure writestream(fnam: string; txt: string);
var
strm: TFileStream;
n: longint;
begin
strm := TFileStream.Create(fnam, fmCreate);
n := Length(txt);
try
strm.Position := 0;
strm.Write(txt[1], n);
finally
strm.Free;
end;
end;