c++ - The difference between QDataStream and QByteArray - 


qtemporaryfile tf; tf.open (); qdatastream tfbs (&tf); tfbs << "hello\r\n" << "world!\r\n"; const int pos = int (tf.pos ());  qbytearray ba; ba.append ("hello\r\n"); ba.append ("world!\r\n"); const int size = ba.size ();

basically question is, doing wrong? why pos > size? should not using << ? should not using qdatastream?

edit: there way configure qdatastream or qtemporaryfile << operator doesn't prepend strings 32bit lengths , store null terminators in file? calling qdatastream::writebytes when have series of quoted strings , qstrings makes ugly code.

the answer in docs. i'm not going go on qbytearray, believe it's obvious working expected.

the qdatastream operator<<(char*) overload evaluates the writebytes() function.

this function outputs:

writes length specifier len , buffer s stream , returns reference stream. len serialized quint32, followed len bytes s. note data not encoded.

so "hello\r\n", expect output be:

0,0,0,8,'h','e','l','l','o','\r','\n',0

the 4-byte length, followed bytes string. string-ending null being added end, account otherwise mysterious 2 bytes.


Comments

Post a Comment

Popular posts from this blog

Why does Ruby on Rails generate add a blank line to the end of a file? -

running rails generate controller foo home results in: class foocontroller < application controller def home end end (there's nothing on line in actual file, blank line) is there purpose blank line? it's common use newline indicate end of line, last line. many editors (like vi, use) add in newline silently. consensus text files (especially in unix world) should end in newline, , there have been problems historically if wasn't present. why should text files end newline? the tool used count lines in file "wc" counts newlines in file, without trailing newline show 3 instead of 4. it improves readability of templates used in generator. consider: https://github.com/rails/rails/blob/master/railties/lib/rails/generators/rails/controller/templates/controller.rb to remove trailing newline, template have last line of: end<% end -%> instead of: end <% end -%> that seems less readable me. the discussion below refers ...
Read more

node.js - Bad Request - node js ajax post -

i'm using express 3.0 , node v0.11.0. have button submits form , i'm using ajax post data json object node server. client code is: $('#contact').submit(function(e) { console.log('submit called'); var formdata = json.stringify($('form').serializeobject()); console.log(formdata); $.ajax({ url: "http://localhost:3000/savedata/", type: "post", datatype: 'json', data: {objectdata: formdata}, contenttype: "application/json", complete: function() { console.log('process complete'); }, success: function(data) { console.log('process sucess'); }, error: function() { console.log('process error'); }, }); return false; }); then on server: var express = require('express'); var app = express(); app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.bodyparser());...
Read more

keyboard - Smiles and long press feature in Android -

i've created android keyboard. how add features inserting smilies, , using long keypresses display symbols? to create long-press behavior allows select several options pop-up menu, follow guide (specifically pop-up menu section): http://developer.android.com/guide/topics/ui/menus.html smileys (also known emoticons) combination of keys, understood programs , parsed same way. have do, when clicks smiley face on keyboard, simulate pressing of key combination matching emoticon. example, when clicks smiley, should simulate key presses ':' , ')' :). here's list of emoticons: http://en.wikipedia.org/wiki/list_of_emoticons
Read more