c# - Strange behavior of WebReponse.GetStream -

i'm writing web downloader , have met strange problem. sample code:

 int chunk;  var request = webrequest.create(uri) httpwebrequest;    using (webresponse response = request.getresponse())   {       using (var responsestream = response.getresponsestream())       {            using (stream file = file.create(filepath))            {                long bytereaded = 0;                long contentlength = response.contentlength;                while (bytereaded < contentlength)                {                     long bytescounttoread = contentlength - bytereaded > chunk ? chunk : contentlength - bytereaded;                     byte[] buffer = new byte[bytescounttoread];                     responsestream.read(buffer, 0, buffer.length);                     file.write(buffer, 0, buffer.length);                     bytereaded += bytescounttoread;                 }             }       }   } 

problem : when 'chunk' variable == 1 or 2 bytes it's ok. when size larger - images become disturbed! i've figured out download speed(response reading speed), because when set larger size of chunk , insert thread.sleep(time) @ last line of while cycle, images stay normal. wish me.

it's not strange @ - you're misusing streams. you're assuming single call read read whole of buffer you've asked for. that's not case - can return less. should change this:

responsestream.read(buffer, 0, buffer.length); file.write(buffer, 0, buffer.length); bytereaded += bytescounttoread; 

to:

int chunkread = responsestream.read(buffer, 0, buffer.length); file.write(buffer, 0, chunkread); bytereaded += chunkread; 

you should never ignore return value of stream.read.

additionally, there's no need create new byte array on each iteration.

finally, if you're using .net 4, of can written much more simply:

using (var responsestream = response.getresponsestream()) {     using (stream file = file.create(filepath))     {         responsestream.copyto(file);     } } 

(or use webclient / httpclient start with...)