c# - Converting base64 value to number -


i receiving data regarding vehicle speeds. have no control on input format, need use data.

the data sent me base64 encoded values. apparently, data started out number in little endian format. currently, code this:

public int b64toint(string input){      byte[] output = convert.frombase64string(input);     array.reverse(output);     if (output.length == 1)     {         return (int)output[0];     }     else if (output.length == 2)     {         return (int)bitconverter.toint16(output, 0);     }     else     {         return bitconverter.toint32(output, 0);     } }

this works values receive, not all. way, convert value mph, need divide 1150.78.

the following value works: aab6qg== converts 27.19720537374 mph.

the following value not work: aa09 apparently, length of output array 3 bytes , don't know how handle situation.

the error message is: "destination array not long enough copy items in collection. check array index , length."

you build number yourself, decoded bytes. is, rather bitconverter.toint16 or bitconverter.toint32, following. (note don't reverse array.)

byte[] output = convert.frombase64string(input); console.writeline(output.length); int rslt = 0; (int = 0; < output.length; ++i) {     rslt <<= 8;     rslt += output[i]; } console.writeline(rslt); console.writeline((double)rslt / 1150.78);

given input string of "aab6qg==", produces 27.1972053737465. "aa09" produces 2.94495907123864.

what i'm doing here fitting 4 bytes 32-bit integer. <<= 8 means "shift left 8 bits". effect bytes shifted 1 position left each time through loop.

so, given array { 00, 00, 7a, 42 }, rslt starts @ 0. result stays @ 0 until 3rd byte. then:

rslt += output[2];  // rslt = 0x0000007a // next time through loop rslt <<= 8          // rslt = 0x00007a00 rslt += output[3];  // rslt = 0x00007a42

Comments

Post a Comment

Popular posts from this blog

jquery - How can I dynamically add a browser tab? -

since using iframes house external pages are, accounts "not preferred method" , disallowed sites (flickr, one), want dynamically generate browser tabs. e.g., when user submits form, want dynamically generate tab on browser in response submitted. e.g., might want add new tab url like: http://www.bigsurgarrapata.com/contact how in jquery? you want form target attribute action attribute. http://www.w3schools.com/tags/att_form_target.asp browsers have ultimate control on result of target attribute open new tab value of _blank. <form action="contact_submit.php" target="_blank" method="post">
Read more

node.js - Getting the socket id,user id pair of a logged in user(s) -

i have web application done using node js , in it,i have authentication system requires users log in before can access pages. have 2 pages,the homepage , updates page. from read docs,a new socket id issued when user opens tab in browser. me being admin,i know socket id of logged in user , more so,the socket id,logged in user id pair logged in users. what method can use socket id,logged in user id pair make sure broadcast realtime info users online?.
Read more

keyboard - C++ GetAsyncKeyState alternative -

i using windows.h library's getasynckeystate function define key pushed on keyboard . here program returns int value of pushed key example. #include <iostream> #include <windows.h> using namespace std; int main (){ char i; for(i=8;i<190;i++){ if(getasynckeystate(i)== -32767){ cout<<int (i)<<endl; } } return 0; } but trying make opengl simple game , function appeared slow . there function not need cycle 180 times , if statement . thanks you're trying make opengl game, you're going use glfw. if that's case can away using glfwgetkey() such: if (glfwgetkey(glfw_key_up) == glfw_press) {...} if (glfwgetkey(glfw_key_down) == glfw_press) {...} that method nicely explained in tutorial 6 opengl-tutorial.org . should start first tutorial of beginners tutorials , later intermediate tutorials . if you're going make win32 window can listen wm_keydown or wm_keyup messages , virtua
Read more