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• retrieve image from sql server in picturebox

  - by user3116296

  I have saved a picture in sql server and now i can not to retrieve image and set it's in picturebox with linq. why byte[] x become null? private void dataGridViewUser_CellClick(object sender, DataGridViewCellEventArgs e) { DataGridViewRow row = dataGridViewUser.CurrentRow; byte[] x=(byte[])row.Cells["Image"].Value; MemoryStream ms1 = new MemoryStream(x); picuser.Image = Bitmap.FromStream(ms1); }

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• Dealing with array of IntPtr

  - by Padu Merloti

  I think I'm close and I bet the solution is something stupid. I have a C++ native DLL where I define the following function: DllExport bool __stdcall Open(const char* filePath, int *numFrames, void** data); { //creates the list of arrays here... don't worry, lifetime is managed somewhere else //foreach item of the list: { BYTE* pByte = GetArray(i); //here's where my problem lives *(data + i * sizeofarray) = pByte; } *numFrames = total number of items in the list return true; } Basically, given a file path, this function creates a list of byte arrays (BYTE*) and should return a list of pointers via the data param. Each pointing to a different byte array. I want to pass an array of IntPtr from C# and be able to marshal each individual array in order. Here's the code I'm using: [DllImport("mydll.dll",EntryPoint = "Open")] private static extern bool MyOpen( string filePath, out int numFrames, out IntPtr[] ptr); internal static bool Open( string filePath, out int numFrames, out Bitmap[] images) { var ptrList = new IntPtr[512]; MyOpen(filePath, out numFrames, out ptrList); images = new Bitmap[numFrames]; var len = 100; //for sake of simplicity for (int i=0; i<numFrames;i++) { var buffer = new byte[len]; Marshal.Copy(ptrList[i], buffer, 0, len); images[i] = CreateBitmapFromBuffer(buffer, height, width); } return true; } Problem is in my C++ code. When I assign *(data + i * sizeofarray) = pByte; it corrupts the array of pointers... what am I doing wrong?

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• Negative number representation across multiple architechture

  - by Donotalo

  I'm working with OKI 431 micro controller. It can communicate with PC with appropriate software installed. An EEPROM is connected in the I2C bus of the micro which works as permanent memory. The PC software can read from and write to this EEPROM. Consider two numbers, B and C, each is two byte integer. B is known to both the PC software and the micro and is a constant. C will be a number so close to B such that B-C will fit in a signed 8 bit integer. After some testing, appropriate value for C will be determined by PC and will be stored into the EEPROM of the micro for later use. Now the micro can store C in two ways: The micro can store whole two byte representing C The micro can store B-C as one byte signed integer, and can later derive C from B and B-C I think that two's complement representation of negative number is now universally accepted by hardware manufacturers. Still I personally don't like negative numbers to be stored in a storage medium which will be accessed by two different architectures because negative number can be represented in different ways. For you information, 431 also uses two's complement. Should I get rid of the headache that negative number can be represented in different ways and accept the one byte solution as my other team member suggested? Or should I stick to the decision of the two byte solution because I don't need to deal with negative numbers? Which one would you prefer and why?

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• .NET SerialPort.Read skipps bytes

  - by Lukas Rieger

  Solution Reading the data byte wise via "port.ReadByte" is too slow, the problem is inside the SerialPort class. i changed it to reading bigger chunks via "port.Read" and there are now no buffer overruns. although i found the solution myself, writing it down helped me and maybe someone else has the same problem and finds this via google... (how can i mark it as answered?) EDIT 2 by setting port.ReadBufferSize = 2000000; i can delay the problem for ~30 seconds. so it seems, .Net really is too slow... since my application is not that critical, i just set the buffer to 20MB, but i am still interested in the cause. EDIT i just tested something i had not thought of before (shame on me): port.ErrorReceived += (object self, SerialErrorReceivedEventArgs se_arg) => { Console.Write("| Error: {0} | ", System.Enum.GetName(se_arg.EventType.GetType(), se_arg.EventType)); }; and it seems that i have an overrun. Is the .Net implementation too slow for 500k or is there an error on my side? Original Question i built a very primitive oszilloscope (avr, which sends adc data over uart to an ftdi chip). On the pc side i have a WPF Programm that displays this data. The Protokoll is: two sync bytes (0xaffe) - 14 data bytes - two sync bytes - 14 data bytes - ... i use 16bit values, so inside the 14 data bytes are 7 channels (lsb first). I verified the uC Firmware with hTerm, and it does send and receive everything correct. But, if i try to read the data with C#, sometimes some bytes are lost. The oszilloscop programm is a mess, but i created a small sample application, which has the same symptoms. I added two extension methods to a) read one byte from the COM Port and ignore -1 (EOF) and b) wait for the sync pattern. The sample programm first syncs onto the data stream by waiting for (0xaffe) and then compares the received bytes with the expected values. the loop runs a few times until an assert failed message pops up. I could not find anything about lost bytes via google, any help would be appreciated. Code using System; using System.Collections.Generic; using System.Diagnostics; using System.IO.Ports; using System.Linq; using System.Text; using System.Threading.Tasks; namespace SerialTest { public static class SerialPortExtensions { public static byte ReadByteSerial(this SerialPort port) { int i = 0; do { i = port.ReadByte(); } while (i < 0 || i > 0xff); return (byte)i; } public static void WaitForPattern_Ushort(this SerialPort port, ushort pattern) { byte hi = 0; byte lo = 0; do { lo = hi; hi = port.ReadByteSerial(); } while (!(hi == (pattern >> 8) && lo == (pattern & 0x00ff))); } } class Program { static void Main(string[] args) { //500000 8n1 SerialPort port = new SerialPort("COM3", 500000, Parity.None, 8, StopBits.One); port.Open(); port.DiscardInBuffer(); port.DiscardOutBuffer(); //Sync port.WaitForPattern_Ushort(0xaffe); byte hi = 0; byte lo = 0; int val; int n = 0; // Start Loop, the stream is already synced while (true) { //Read 7 16-bit values (=14 Bytes) for (int i = 0; i < 7; i++) { lo = port.ReadByteSerial(); hi = port.ReadByteSerial(); val = ((hi << 8) | lo); Debug.Assert(val != 0xaffe); } //Read two sync bytes lo = port.ReadByteSerial(); hi = port.ReadByteSerial(); val = ((hi << 8) | lo); Debug.Assert(val == 0xaffe); n++; } } } }

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• receive string with chars

  - by Meloun

  Hi all, i am quite new in python. I am receiving (through pyserial) string with data values. How can I parse these data to particular data structure? I know that 0-1 byte : id 2-5 byte : time1 =>but little endian (lsb first) 6-9 byte : time2 =>but little endian (lsb first) and I looking for a function: def parse_data(string): data={} data['id'] = ?? data['time1'] = ?? data['time2'] = ?? return data thanks

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• WPF: Convert memory stream to BitmapImage?

  - by David Veeneman

  I have an image that was originally a PNG that I have converted to a byte[] and saved in a database. Originally, I simply read the PNG into a memory stream and converted the stream into a byte[]. Now I want to read the byte[] back and convert it to a BitmapImage, so that I can bind a WPF Image control to it. I am seeing a lot of contradictory and confusing code online to accomplish the task of converting a byte[] to a BitmapImage. I am not sure whether I need to add any code due to the fact that the image was originally a PNG. Can anyone provide the code to convert the stream to a BitmapImage? Thanks for your help.

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• C# :: Checking if a bit is set or not

  - by Manjoor

  Shhow me a very simple one line example in C# to check if a given bit is set in given byte function signature should be like bool IsBitSet(Byte b,byte nPos) { return .....; } The Speed vs

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• Mono & DeflateStream

  - by ILya

  I have a simple code byte[] buffer = Encoding.UTF8.GetBytes("abracadabra"); MemoryStream ms = new MemoryStream(); DeflateStream ds = new DeflateStream(ms, CompressionMode.Compress, false); ms.Write(buffer, 0, buffer.Length); DeflateStream ds2 = new DeflateStream(ms, CompressionMode.Decompress, false); byte[] buffer2 = new byte[ms.Length]; ds2.Read(buffer2, 0, (int)ms.Length); Console.WriteLine(Encoding.UTF8.GetString(buffer2)); And when reading from ds2, i have the following: Stacktrace: at (wrapper managed-to-native) System.IO.Compression.DeflateStream.ReadZStream (intptr,intptr,int) <0x00004 at (wrapper managed-to-native) System.IO.Compression.DeflateStream.ReadZStream (intptr,intptr,int) <0x00004 at System.IO.Compression.DeflateStream.ReadInternal (byte[],int,int) [0x00031] in C:\cygwin\tmp\monobuild\build\BUILD\mono-2.6.3\mcs\class\System\System.IO.Compression\DeflateStream.cs:192 at System.IO.Compression.DeflateStream.Read (byte[],int,int) [0x00086] in C:\cygwin\tmp\monobuild\build\BUILD\mono-2.6.3\mcs\class\System\System.IO.Compression\DeflateStream.cs:214 at testtesttest.MainClass.Main (string[]) [0x00041] in C:\Users\ilukyanov\Desktop\Cassini\GZipDemo\Main.cs:27 at (wrapper runtime-invoke) .runtime_invoke_void_object (object,intptr,intptr,intptr) This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. This problem appears in Mono 2.6.1 & 2.6.3... Is there any known way to successfully read from DeflateStream in Mono? Or maybe there are some third-party open-source assemblies with the same functionality?

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• How to easily Generate Synth Chords Sounds in Android?

  - by barata7

  How to easily Generate Synth Chords Sounds in Android? I wanna be able to generate dynamically an in game Music using 8bit. Tried with AudioTrack, but did not get good results of nice sounds yet. Any examples out there? I have tried the following code without success: public class BitLoose { private final int duration = 1; // seconds private final int sampleRate = 4200; private final int numSamples = duration * sampleRate; private final double sample[] = new double[numSamples]; final AudioTrack audioTrack; public BitLoose() { audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRate, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_8BIT, numSamples, AudioTrack.MODE_STREAM); audioTrack.play(); } public void addTone(final int freqOfTone) { // fill out the array for (int i = 0; i < numSamples; ++i) { sample[i] = Math.sin(2 * Math.PI * i / (sampleRate / freqOfTone)); } // convert to 16 bit pcm sound array // assumes the sample buffer is normalised. final byte generatedSnd[] = new byte[numSamples]; int idx = 0; for (final double dVal : sample) { // scale to maximum amplitude final short val = (short) ((((dVal * 255))) % 255); // in 16 bit wav PCM, first byte is the low order byte generatedSnd[idx++] = (byte) (val); } audioTrack.write(generatedSnd, 0, sampleRate); } public void stop() { audioTrack.stop(); }

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• Read a file with 2048 bytes

  - by Suresh S

  Guys i have a file which has only one line. The file has no encoding it is a simple text file with single line. For every 2048 byte in a line , there is new record of 151 byte (totally 13*151 byte = 1945 records + 85 byte empty space). similarly for the next 2048 bytes. What is the best file i/o to use? i am thinking of reading 2048 bytes from file and storing it in an array . while (offset < fileLength &&(numRead=in.read(recordChunks, offset,alength)) >= 0) { } how can i get from the read statement only 2048 bytes at a time . i am getting IndexOutofBoundException.

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• encryption problem for wlan profile

  - by Jassi

  i am trying to encrypt keyMaterial element from wireless profile. so I want to convert byte array into OLECHAR but it is giving me wrong output not key sea the below code you may know the solution... DATA_BLOB in; DATA_BLOB out; BYTE pin=(BYTE)"FIPL2"; DWORD din=strlen((char*)pin)+1; in.pbData = pin; in.cbData = din; if(CryptProtectData(&in,L"what is it",NULL,NULL,NULL,0,&out)) { BYTE *b=out.pbData; USES_CONVERSION; bstr=SysAllocString(W2BSTR((const WCHAR *)b)); HRCALL(peSubS222->put_text(bstr), ""); SysFreeString(bstr); bstr=NULL; } else { cout<<"NOOOOOOOOOOOOOOOO :("; } what is missing please help me out

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• what is the best method of concatenating a series of binary files into one file?

  - by Andrew

  hello everyone i have a series of PDF byte arrays in a arraylist files that i wish to concatenate into one file, currently when the PDF application trys to open the file is it corrupted: foreach (byte[] array in files) { using (Stream s = new MemoryStream(downloadbytes)) { s.Write(array, 0, array.Length); } } downloadbytes is the resultant concatenated array of bytes below is another implementation which also failed foreach (byte[] array in files) { System.Buffer.BlockCopy(array, 0, downloadbytes, offset, array.Length); offset += array.Length; } any pointers?

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• Null reference for first memory address between 0 - 65535

  - by Terry

  I would like to understand a bit more about memory and I was unable to find it from Google, please forgive me if this is silly question. How come the following code, accessing memory address 0(and up to 65535) in C# would throw NullReferenceException byte* pointer = (byte*)0; byte test = *pointer; Thanks a lot in advance!

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• Socket receive buffer size

  - by Kanishka

  Is there a way to determine the receive buffer size of a TCPIP socket in c#. I am sending a message to a server and expecting a response where I am not sure of the receive buffer size. IPEndPoint ipep = new IPEndPoint(IPAddress.Parse("192.125.125.226"),20060); Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); server.Connect(ipep); String OutStr= "49|50|48|48|224|48|129|1|0|0|128|0|0|0|0|0|4|0|0|32|49|50"; byte[] temp = OutStr.Split('|').Select(s => byte.Parse(s)).ToArray(); int byteCount = server.Send(temp); byte[] bytes = new byte[255]; int res=0; res = server.Receive(bytes); return Encoding.UTF8.GetString(bytes);

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• Is there a simpliest way of doing this?

  - by Tom Brito

  Is there a simpler way of implement this? Or a implemented method in JDK or other lib? /** * Convert a byte array to 2-byte-size hexadecimal String. */ public static String to2DigitsHex(byte[] bytes) { String hexData = ""; for (int i = 0; i < bytes.length; i++) { int intV = bytes[i] & 0xFF; // positive int String hexV = Integer.toHexString(intV); if (hexV.length() < 2) { hexV = "0" + hexV; } hexData += hexV; } return hexData; } public static void main(String[] args) { System.out.println(to2DigitsHex(new byte[] {8, 10, 12})); } the output is: "08 0C 0A" (without the spaces)

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• Checked and Unchecked operators don't seem to be working when...

  - by flockofcode

  1) Is UNCHECKED operator in effect only when expression inside UNCHECKED context uses an explicit cast ( such as byte b1=unchecked((byte)2000); ) and when conversion to particular type can happen implicitly? I’m assuming this since the following expression throws a compile time error: byte b1=unchecked(2000); //compile time error 2) a) Do CHECKED and UNCHECKED operators work only when resulting value of an expression or conversion is of an integer type? I’m assuming this since in the first example ( where double type is being converted to integer type ) CHECKED operator works as expected: double m = double.MaxValue; b=checked((byte)m); // reports an exception , while in second example ( where double type is being converted to a float type ) CHECKED operator doesn’t seem to be working. since it doesn't throw an exception: double m = double.MaxValue; float f = checked((float)m); // no exception thrown b) Why don’t the two operators also work with expressions where type of a resulting value is of floating-point type? 2) Next quote is from Microsoft’s site: The unchecked keyword is used to control the overflow-checking context for integral-type arithmetic operations and conversions I’m not sure I understand what exactly have expressions and conversions such as unchecked((byte)(100+200)); in common with integrals? Thank you

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• How to find Key and IV value from .Net to PHP

  - by PHP-Prabhu

  Can any one please let me know is there any way to find a solution for the below stuffs. I need to find out the KEY and IV value from the below byte array. the byte array in .net and this has to be convert into KEY(string) and IV(string) via PHP. private static readonly byte[] Key = { 0xda, 0x3c, 0x35, 0x6f, 0xbd, 0xd, 0x87, 0xf0, 0x9a, 0x7, 0x6d, 0xab, 0x7e, 0x82, 0x36, 0xa, 0x1a, 0x5a, 0x77, 0xfe, 0x74, 0xf3, 0x7f, 0xa8, 0xaa, 0x4, 0x11, 0x46, 0x6b, 0x2d, 0x48, 0xa1 }; private static readonly byte[] IV = { 0x6d, 0x2d, 0xf5, 0x34, 0xc7, 0x60, 0xc5, 0x33, 0xe2, 0xa3, 0xd7, 0xc3, 0xf3, 0x39, 0xf2, 0x16 };

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• Logic: Best way to sample & count bytes of a 100MB+ file

  - by Jami

  Let's say I have this 170mb file (roughly 180 million bytes). What I need to do is to create a table that lists: all 4096 byte combinations found [column 'bytes'], and the number of times each byte combination appeared in it [column 'occurrences'] Assume two things: I can save data very fast, but I can update my saved data very slow. How should I sample the file and save the needed information? Here're some suggestions that are (extremely) slow: Go through each 4096 byte combinations in the file, save each data, but search the table first for existing combinations and update it's values. this is unbelievably slow Go through each 4096 byte combinations in the file, save until 1 million rows of data in a temporary table. Go through that table and fix the entries (combine repeating byte combinations), then copy to the big table. Repeat going through another 1 million rows of data and repeat the process. this is faster by a bit, but still unbelievably slow This is kind of like taking the statistics of the file. NOTE: I know that sampling the file can generate tons of data (around 22Gb from experience), and I know that any solution posted would take a bit of time to finish. I need the most efficient saving process

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• Reading files with Java

  - by sikas

  I would like to know how can I read a file byte by byte then perform some operation every n bytes. for example: Say I have a file of size = 50 bytes, I want to divide it into blocks each of n bytes. Then each block is sent to a function for some operations to be done on those bytes. The blocks are to be created during the read process and sent to the function when the block reaches n bytes so that I don`t use much memory for storing all blocks. I want the output of the function to be written/appended on a new file. This is what I've reached to read, yet I don't know it it is right: fc = new JFileChooser(); File f = fc.getSelectedFile(); FileInputStream in = new FileInputStream(f); byte[] b = new byte[16]; in.read(b); I haven't done anything yet for the write process.

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• Forcibly clear memory in java

  - by MBennett

  I am writing an application in java that I care about being secure. After encrypting a byte array, I want to forcibly remove from memory anything potentially dangerous such as the key used. In the following snippet key is a byte[], as is data. SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec); byte[] encData = cipher.doFinal(data, 0, data.length); Arrays.fill(key, (byte)0); As far as I understand, the last line above overwrites the key with 0s so that it no longer contains any dangerous data, but I can't find a way to overwrite or evict secretKeySpec or cipher similarly. Is there any way to forcibly overwrite the memory held by secretKeySpec and cipher, so that if someone were to be able to view the current memory state (say, via a cold boot attack), they would not get access to this information?

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• C# underlying types of enums

  - by Marlon

  What is the point of having enum SomeEnum : byte // <---- { SomeValue = 0x01, ... } when you have to make a cast just to assign it to the same type of variable as the enums underlying type? byte b = (byte)SomeEnum.SomeValue;

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• python on the web, does it compile down to bytecode or is it more like php?

  - by Blankman

  Does python compile down to some byte code or is it rendered on the fly each time like php/asp? From my readings I read it has its own byte code format, so i figured it was like java/.net where it compiles into a intermediate language/byte code. so it is more effecient in that respect that php right?

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• How to split and join array in C++?

  - by Richard Knop

  I have a byte array like this: lzo_bytep out; // my byte array size_t uncompressedImageSize = 921600; out = (lzo_bytep) malloc((uncompressedImageSize + uncompressedImageSize / 16 + 64 + 3)); wrkmem = (lzo_voidp) malloc(LZO1X_1_MEM_COMPRESS); // Now the byte array has 802270 bytes r = lzo1x_1_compress(imageData, uncompressedImageSize, out, &out_len, wrkmem); How can I split it into smaller parts under 65,535 bytes (the byte array is one large packet which I want to sent over UDP which has upper limit 65,535 bytes) and then join those small chunks back into a continuous array?

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• Is the Google Annotations Gallery useful in production code?

  - by cafe

  I could actually see a use for the Google Annotations Gallery in real code: Stumble across code that somehow works beyond all reason? Life's short. Mark it with @Magic and move on: @Magic public static int negate(int n) { return new Byte((byte) 0xFF).hashCode() / (int) (short) '\uFFFF' * ~0 * Character.digit ('0', 0) * n * (Integer.MAX_VALUE * 2 + 1) / (Byte.MIN_VALUE >> 7) * (~1 | 1); } This is a serious question. Could this be used in an actual code review?

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• How to pass a file (read from Java) most effectively to a native method?

  - by soc

  Hi, I have approx. 30000 files (1MB each) which I want to put into a native method, which requires just an byte array and the size of it as arguments. I looked through some examples and benchmarks (like http://nadeausoftware.com/articles/2008/02/java_tip_how_read_files_quickly) but all of them do some other fancy things. Basically I don't care about the contents of the file, I don't want to access something in that file or the byte array or do anything else with it. I just want to put a file into a native method which accepts an byte array as fast as possible. At the moment I'm using RandomAccessFile, but that's horribly slow (10MB/s). Is there anything like byte[] readTheWholeFile(File file){ ... } which I could put into native void fancyCMethod(readTheWholeFile(myFile), myFile.length()) What would you suggest?

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