Test tstreamwriter and tstreamreader

Both tstreamwriter and tstringwriter inherit from the abstract class: ttextwriter;
Both tstreamreader and tstringreader inherit from the abstract class: ttextreader.

They have similar functions, but tstreamwriter and tstreamreader have the "stream" feature and are suitable for reading and writing string streams.

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, stdctrls; Type tform1 = Class (tform) button1: tbutton; button2: tbutton; button3: tbutton; button4: tbutton; Procedure submit (Sender: tobject ); end; var form1: tform1; implementation {$ R *. DFM} const filepath = 'C: \ temp \ test.txt '; // It seems to be a stream operation. In fact, the non-string type written is also converted to the string procedure tform1.button1click (Sender: tobject ); vaR Writer: tstreamwriter; reader: tstreamreader; begin Writer: = tstreamwriter. create (filepath); writer. writeline ('string'); writer. writeline (123); writer. writeline (true); writer. writeline (3.14); writer. close; writer. free; reader: = tstreamreader. create (filepath); showmessage (reader. readtoend); reader. close; reader. free; end; // you can specify the character encoding procedure tform1.button2click (Sender: tobject); var Writer: tstreamwriter; reader: tstreamreader; begin {parameter 2 is added after an existing file if it is true; false is a new file} Writer: = tstreamwriter. create (filepath, false, tencoding. unicode); writer. writeline ('in case of Delphi blog'); writer. close; writer. free; reader: = tstreamreader. create (filepath, tencoding. unicode); showmessage (reader. readtoend); reader. close; reader. free; end; // when encoding is not specified, the default value is utf8procedure tform1.button3click (Sender: tobject); var Writer: tstreamwriter; reader: tstreamreader; begin Writer: = tstreamwriter. create (filepath); writer. write ('in case of Delphi blog'); writer. close; writer. free; reader: = tstreamreader. create (filepath); showmessage (reader. currentencoding. classname); {tutf8encoding} reader. endofstream; reader. close; reader. free; end; // can be created based on another tstream. From the perspective of basestream, it is indeed a stream procedure tform1.button4click (Sender: tobject); var Writer: tstreamwriter; reader: tstreamreader; begin Writer: = tstreamwriter. create (tfilestream. create (filepath, fmcreate), tencoding. utf8); writer. write ('in case of Delphi blog'); writer. basestream. free; writer. close; writer. free; reader: = tstreamreader. create (tfilestream. create (filepath, fmopenread), tencoding. utf8); showmessage (reader. readline); {in case of Delphi blog} reader. basestream. free; reader. close; reader. free; end.