Difference between revisions of "TFileStream"
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Jump to navigationJump to search (Remove incorrect statement that TFileStream reads entire file. Avoid FreeAndNil of local variables.) |
(Fix not setting result in "read 8 bytes" example) |
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|} | |} | ||
| − | * read entire file ''fnam'' | + | * read entire file ''fnam'' into a string. |
| − | <syntaxhighlight> | + | |
| + | <syntaxhighlight lang="pascal"> | ||
function readstream(fnam: string): string; | function readstream(fnam: string): string; | ||
var | var | ||
| Line 47: | Line 48: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| − | * Write a string ''txt'' to file ''fnam''. | + | * read 8 bytes of ''fnam'' into a byte array: |
| − | <syntaxhighlight> | + | |
| + | <syntaxhighlight lang="pascal"> | ||
| + | .. | ||
| + | type | ||
| + | TByte8Array = array [0..7] of byte; | ||
| + | .. | ||
| + | function readstream(fnam: string; position= integer): TByte8Array; | ||
| + | var | ||
| + | strm : TFileStream; | ||
| + | begin | ||
| + | strm := TFileStream.Create(fnam, fmOpenRead or fmShareDenyWrite); | ||
| + | try | ||
| + | strm.Position:=position; | ||
| + | strm.Read (Result[0],8); | ||
| + | finally | ||
| + | strm.Free; | ||
| + | end; | ||
| + | end; | ||
| + | </syntaxhighlight> | ||
| + | |||
| + | * Write a string ''txt'' to the file ''fnam''. | ||
| + | |||
| + | <syntaxhighlight lang="pascal"> | ||
procedure writestream(fnam: string; txt: string); | procedure writestream(fnam: string; txt: string); | ||
var | var | ||
| Line 66: | Line 89: | ||
== See also == | == See also == | ||
| + | * [[File types]] | ||
* [[doc:rtl/classes/tfilestream.html|TFileStream doc]] | * [[doc:rtl/classes/tfilestream.html|TFileStream doc]] | ||
* [[doc:rtl/classes/tstream.html|TStream doc]] | * [[doc:rtl/classes/tstream.html|TStream doc]] | ||
Latest revision as of 16:22, 12 April 2022
│
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 into 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;
- read 8 bytes of fnam into a byte array:
..
type
TByte8Array = array [0..7] of byte;
..
function readstream(fnam: string; position= integer): TByte8Array;
var
strm : TFileStream;
begin
strm := TFileStream.Create(fnam, fmOpenRead or fmShareDenyWrite);
try
strm.Position:=position;
strm.Read (Result[0],8);
finally
strm.Free;
end;
end;
- Write a string txt to the 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;
