Database Users

data type conversion in eVC++

Hello Everyone
I hope this is not too trivial a question. I am new to eVC. I would like to know how to convert from data type LONG to data type CHAR OR STRING in eVC.
Long myLong=1134.67
In VB the conversion will simply be
myString=STR(myLong)
How can I achieve this in eVC++?
Also someone please recommend some good books on eVC++.
Thanks.
ajanaman

evc++ is just like vc++
which is just like c++ with mfc on top of it
to do simple type casts you do
x=(Type)y;
here are some links also included dynamic type casts
http://www.cplusplus.com/doc/tutorial/typecasting.html
http://www.torjo.com/win32gui/doc/window_casting.html

Hello gsmtexts!
First I would like to point out that in C++ LONG data type is a 4 byte signed integer (in your example you use a floating point value).
Second I assume that by converting you mean representing the number as a string of characters an not just letting the computer assume that the variable contains ASCII values instead of a number.
Here's how you do it:
C++ language doesn't have string data type instead you use an array of char.
Example:
Code:
char myStr[255]; //you have a string of up to 255 ASCII chars.
double myVal = 50.1234; //a double precision floating point value
_gcvt(myVal, 6, myStr); //convert the string
You could use one of the functions (you can search the MSDN site for more details): _gcvt, _ecvt, _fcvt, but there is a simpler way as well:
Code:
WCHAR myStr[255]; //win CE works with Unicode strings.
float myVal = 1.2345; //the value
swprintf(myStr, L"The value: %f", myVal); //creates a string: 'The value: 1.2345'
Finally if you are using MFC:
Code:
CString str;
float myVal = 1.2345;
str.Format(_T("The value: %f"), myVal);
As for books I can only recommend "Teach yourself C++", by Jesse Liberty, it got me started in C++ programming.
Good luck.

Dear levenum
many thanks - I have sratched my head for nearly a week and you gave me the solution just like that. _gcvt did it. u are a wonderful guru.
ajanaman

You are welcome gsmtexts!
But I am far from being a guru. I just like programming so I picked up a book or two and the ball started rolling. 8)
Anyway, since you chose to use _gcvt you should know that in order to use the string you get with windows API's like SetWindowText you will have to convert it to Unicode:
Code:
WCHAR uniBuffer[50]; //Unicode buffer
char myString[50]; //ASCII buffer
_gcvt(1.2345, 5, myString); //convert value to string
mbstowcs(uniBuffer, myString, 50); //convert ASCII string to Unicode

The standard c++ way would be:
double d=122.332;
std:stringstream oss;
oss << d;
std::string mystring=oss.str();

The standard c++ way would be:
double d=122.332;
std:stringstream oss;
oss << d;
std::string mystring=oss.str();

Learning how to program for Windows Mobile?

I've done some searching, and I know Windows CE uses Win32, which I know to an extent. I was curious if there are any good free resources for learning WinCE-Win32, or if I should simply use my existing books for MFC/Win32. Microsoft's site kinda sketchy, and MSDN not being very useful. I did get Microsoft Embedded Visual C++ working and compiled a test app which worked on my MDA and on the emulator.

i would just start coding
miniMFC and compact .net framework is soo close it's only
some controls and options you dont have
ortherwise it's the same thing
learning by doing and having ones fingers down and dirty
into the code is where you learn the most

Yep, that's just how I learned when I switched to coding for PPCs.
Any way here are a few major differences to start you off:
1) All API's that use strings are in UNICODE. ASCII versions were removed.
2) For most API's that have an 'ext' version the regular version was removed. Example: ExtTextOut - yes, TextOut - no.
3) When dealing with files, all paths must be absolute. No '..\file.x' and 'file.x' will give you the file in device root and not the app directory.
And here is a nice site for pocket PC specific apps:
www.pocketpcdn.com
Has articles on just about everything from making dialogs not full screen to writing today plug-ins.

levenum said:
Yep, that's just how I learned when I switched to coding for PPCs.
Any way here are a few major differences to start you off:
1) All API's that use strings are in UNICODE. ASCII versions were removed.
2) For most API's that have an 'ext' version the regular version was removed. Example: ExtTextOut - yes, TextOut - no.
3) When dealing with files, all paths must be absolute. No '..\file.x' and 'file.x' will give you the file in device root and not the app directory.
And here is a nice site for pocket PC specific apps:
www.pocketpcdn.com
Has articles on just about everything from making dialogs not full screen to writing today plug-ins.
Click to expand...
Click to collapse
I knew about how everything was Unicode. Is there an easy way to create unicode strings? I remember there was something in MFC macro like TEXT() that did something like that, but the specifics are missing. I remember there was a knowledge base article on this, but I can't find it.
Also, what's the difference between the Ext version and the non-ext versions of an app?
EDIT: Unless I'm mistaken, I just need to put my strings in _T("*string*")

Yes, you're right, this is how you write strings in your code:
Code:
WCHAR uniStr[] = L"Unicode string";
or if you are using MFC:
Code:
CString uniStr = _T("Unicode string");
and if you have a ASCII string you want converted to UNICODE
use mbstowcs function. (CString class has a built in conversion)
As for the 'ext' API's they just give you more parameters to better control the result of whatever they are doing. In desktop windows if you didn't want to call a function with 10 parameters you usually had a simpler version of it where some things were default.
Example:
Code:
BOOL TextOut(
HDC hdc, // handle to DC
int nXStart, // x-coordinate of starting position
int nYStart, // y-coordinate of starting position
LPCTSTR lpString, // character string
int cbString // number of characters
); //5 parameters
BOOL ExtTextOut(
HDC hdc, // handle to DC
int X, // x-coordinate of reference point
int Y, // y-coordinate of reference point
UINT fuOptions, // text-output options
CONST RECT *lprc, // optional dimensions
LPCTSTR lpString, // string
UINT cbCount, // number of characters in string
CONST INT *lpDx // array of spacing values
); // 8 parameters

what would be your suggestion for a newbie to learn programming for PPC?
I'm beggining to have interest in doing this but have absolutely no idea where to start.
thanks for any advise.

For complete newbies, I wrote this post a while back:
http://forum.xda-developers.com/viewtopic.php?p=209136#209136
V

VB.NET how to pass a struct? anyone?

Anyone know how to pass a pointer to a struct in VB.NET that could help me out?
" pGPSPosition
Pointer to a GPS_POSITION structure. On return, this structure is filled with location data obtained by the GPS Intermediate Driver. The dwValidFields member of the GPS_POSITION instance specifies which fields of the instance are valid."
This is from a link on MS site: (http://msdn2.microsoft.com/en-us/library/bb202050.aspx)
So how do I do this in VB?
Looking for a little love here...
TIA,

WM6 SDK contains the sample with the complete wrapper around the GPS intermediate driver in the managed code
But one warning - on some devices (namely HTC Artemis) the serious bug in some version of code provided by Microsoft to Oem return an error when calling functions this API. Communication with a GPS via serial port is still more reliable for a commercial solutions...

Appreciate the response but do you have any source that I can use with VB? My biggest problem is actually retrieving any information from the GPS device using the "GPSGetPosition" function. (see other link - http://forum.xda-developers.com/showthread.php?p=1979418#post1979418)
"But one warning - on some devices (namely HTC Artemis) the serious bug in some version of code provided by Microsoft to Oem return an error when calling functions this API"
Could you be a little more specific?
TW,

Semi manual marshhalling of structure to pointer:
Dim pointerM As IntPtr = Marshal.AllocHGlobal(Marshal.SizeOf(myStruct))
Marshal.StructureToPtr(myStruct, pointerM, False)
Marshal.FreeHGlobal(pnt)
Ad Artemis and another devices) GPS structure has invalid size from old platform builder and intermediate driver (GPS API) refuse it with error.

RStein,
As I was reading about it appeared that Marshaling was going to have to be used in some way since I'm pretty sure that the struct would need to be passed to the C function.
Which brings me to another Q since it appears your are savy at programing in C - how to convert the following C struct?
The struct appears to have a couple of arrays and a few other enums thats are passed to the function, how is that handled in VB?
DWORD GPSGetPosition(
HANDLE hGPSDevice,
GPS_POSITION *pGPSPosition,
DWORD dwMaximumAge,
DWORD dwFlags
);
typedef struct _GPS_POSITION {
DWORD dwVersion;
DWORD dwSize;
DWORD dwValidFields;
DWORD dwFlags;
SYSTEMTIME stUTCTime;
double dblLatitude;
double dblLongitude;
float flSpeed;
float flHeading;
double dblMagneticVariation;
float flAltitudeWRTSeaLevel;
float flAltitudeWRTEllipsoid;
GPS_FIX_QUALITY FixQuality;
GPS_FIX_TYPE FixType;
GPS_FIX_SELECTION SelectionType;
float flPositionDilutionOfPrecision;
float flHorizontalDilutionOfPrecision;
float flVerticalDilutionOfPrecision;
DWORD dwSatelliteCount;
DWORD rgdwSatellitesUsedPRNs[GPS_MAX_SATELLITES];
DWORD dwSatellitesInView;
DWORD rgdwSatellitesInViewPRNs[GPS_MAX_SATELLITES];
DWORD rgdwSatellitesInViewElevation[GPS_MAX_SATELLITES];
DWORD rgdwSatellitesInViewAzimuth[GPS_MAX_SATELLITES];
DWORD rgdwSatellitesInViewSignalToNoiseRatio[GPS_MAX_SATELLITES];
} GPS_POSITION, *PGPS_POSITION;
Click to expand...
Click to collapse
I had a suggestion to create a library from the C# SDK, how difficult would that be? Would it be easier than trying to convert to VB?
Can you help with that?
Thanks for any feedback...

accelerometer(lg gm750) method signatures

attached the.dll of the lg gm750 in case they serve of something
USER iamspv
First take a look at the Unified Sensor Api at codeplex.
My solution is based on the Samsung sensor class, modified to meet the peculiarities of the LG GM750.
First of all, the import of the DeviceIoControl in NativeMethods.cs must be modified such way dwIoControlCode is type uint, and the buffers are byte:
Code:
[DllImport("coredll", CharSet = CharSet.Auto, SetLastError = true)]
public static extern bool DeviceIoControl(IntPtr hDevice, uint dwIoControlCode, [In] byte[] inBuffer, int nInBufferSize, [Out] byte[] outBuffer, int nOutBufferSize, ref int pBytesReturned, IntPtr lpOverlapped);
After a long time dissassembling the accelsensor.dll and and a lot of trial and error testing I came to this conclusion that works:
The constant that starts/stops data output becomes:
Code:
const uint ACCOnRot = 0x1014EE8;
const uint ACCOffRot = 0x1014EE8;
and for reading values:
Code:
const uint ACCReadValues = 0x1014F10;
The difference between start and stop comes from the input given in DeviceIoControl method as follows:
Code:
Code:
public static LGAccSensor Create()
{
DeviceIoControl(ACCOnRot, new byte[1] {1}, new byte[4] );
return new LGAccSensor();
}
protected override void Dispose(bool disposing)
{
base.Dispose(disposing);
DeviceIoControl(ACCOffRot, new byte[1] {0}, new byte[1] );
}
The DeviceIoControl inside the accelerometer class becomes
Code:
Code:
public static void DeviceIoControl(uint controlCode, byte[] inBuffer, byte[] outBuffer)
{
IntPtr file = NativeMethods.CreateFile("ACC1:", 0, 0, IntPtr.Zero, ECreationDisposition.OpenExisting, 0, IntPtr.Zero);
if (file == (IntPtr)(-1))
throw new InvalidOperationException("Unable to Create File");
try
{
int bytesReturned = 0;
int inSize = sizeof(byte) * inBuffer.Length;
int outSize = sizeof(byte) * outBuffer.Length;
if (!NativeMethods.DeviceIoControl(file, controlCode, inBuffer, inSize, outBuffer, outSize, ref bytesReturned, IntPtr.Zero))
throw new InvalidOperationException("Unable to perform operation.");
}
finally
{
NativeMethods.CloseHandle(file);
}
}
Note that the accelerometer device is called ACC1:.
Further the method that returns the three component vector becomes
Code:
Code:
public override GVector GetGVector()
{
byte[] outBuffer = new byte[4];
DeviceIoControl(ACCReadValues, new byte[1] {1}, outBuffer);
GVector ret = new GVector();
int accx = outBuffer[2];
if (accx <=31)
ret.X = accx/2.17;
else
ret.X = (accx-64)*0.47;
ret.X = -ret.X;
int accy = outBuffer[1] ;
if (accy <=31)
ret.Y = accy/2.17;
else
ret.Y = (accy - 64) * 0.47;
int accz = outBuffer[0] ;
if (accz <=31)
ret.Z = accz/2.17;
else
ret.Z = (accz - 64) * 0.47;
double somefactor = 1; return ret.Scale(somefactor);
}
Note that the when called with AccReadValues parameter, the DeviceIoControl returns three bytes each of them containing a signed 6 bit 2's complement value.Basicly there are values on 6 bit ranging from -32 to +31. In the docs below there are tables that put in correspondence these values with acceleration in range -1.5g +1.5g which are the limits of the device. The code I wrote returns acceleration in meters/second2 where 1g=9.8 m/s2. That information I extracted from the technical specifications of the MMA7660FC accelerometer, as found at(try a google search). Also, the type of the accelerometer circuit is found in the service manual (I only found the service manual for LG GM730 which is pretty close).The same thing I also posted at codeplex.
Reply With Quote
It already works! There is nothing more to do about it than use the code in your applications (I speak as a programmer and for programmers). I only showed everyone interested in developing for LG GM750 the steps to modify the SamsungGSensor class from "Unified Sensor Api" at codeplex to work with a LG. Just get the rest of the code from there and put it toghether.
Now there are two directions:
Direction #1
If you want to develop applications that aim to be portable between HTC, Samsung, LG, Toshiba, etc, and you want to use Unified Sensor Api then..
the person responsible for the unified api project at codeplex should make the update to the library as soon as possible such way the library should keep compatibility with the adressed devices. I'm just contributing with some results. That's because the initial code was not very general (ie. the initial parameter types to deviceiocontrol invoked from coredll didn't work with this solution) I had to make some modifications to the code that work with the LG but affect other devices' sensor classes. Now, if the update doesn't come up soon, no problem, anyone just gets the code from codeplex, adds a new class for LG, copies code from Samsung, renames Samsung with LG, adds my modifications, corrects syntax errors, compiles, et voila . . the library is updated to support LG GM750.
Direction #2
If you develop only for LG, just write a LG class as presented above and don't care about other devices.
If you don't know how to use your new class, the project at codeplex has some examples and you'll easily see inside the code how to instantiate sensors, how to read data at certain moments using a timer, and how to capture screen rotation events.
And for your long awaited joy to see it working, I attached the sensor test program along with a version of sensors.dll compiled by me, that works for GM750.
Now get your fingers toghether on the keyboard and start developing for LG
now should work in an emulator as that one of htc in omnia splitting of what we arrange

great work!
thanks much!

htcemu v0.91 /sensors.dll Problems
Hello all,
when I last November asked for a htcemu for LG750, I have not expected that there will be a emu dll so soon.
Thanks to iamspv and others, we now can use g-sensor apps as normal.
Nearly - some apps does not work or crash.
So my favorite alarm clock, klaxon crashes when alarm is activated. Waterlevel also does not work. It looks that both apps use the managed code dll sensors.dll. Even if I exchange the original dll with the one posted here from beginning of february, it does not work. Does anybody has a solution for this ?
For using landscape mode in app I now got best results with changescreen which works almost perfect. It is also possible to exclude some programs like some LG apps which do not support landscape mode.

how did you make other apps work? on my layla only test works and nothing else

creative232 said:
attached the.dll of the lg gm750 in case they serve of something
Click to expand...
Click to collapse
Did you create a running VS 2008 solution for this?. I'm interested.
Will this work on other LG's?

[Q] convert existing Android UDP (DatagramPacket) code to TCP

I have existing Android code that submits a pre-constructed packet over UDP to a hardware device... however, I now need to convert this code to work over TCP instead in order to be more reliable. Currently the code will send the packet to the device, and wait for a predetermined Timeout time for the Device to "answer" back over the same UDP port and to the source IP. The hardware device listens on both UDP and TCP on the same port numbers.
The UDP code looks like this:
Code:
serverSocket = new DatagramSocket(ListenPort);
{
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddressOut);
serverSocket.send(sendPacket);
serverSocket.setSoTimeout(TimeOut);
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
serverSocket.receive(receivePacket);
byte[] tempDataBuf = Arrays.copyOfRange(receiveData, 0, receivePacket.getLength());
MsgReply.ApplyMessageData(tempDataBuf);
System.out.println("RECEIVED: " + MsgReply.toString());
publishProgress(MsgReply.toString().getBytes());
}
Can anyone assist me in converting this code into TCP format?
Appreciate any help!
PS...I asked this question on stackoverflow too, but got no response... heard XDA started a programming forum, so figured I'll give this a bash

Code:
try {
s=new Socket(InetAddress.getByName("192.168.0.2"),2020);
in = new BufferedReader(new InputStreamReader(s.getInputStream()));
out= new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
//send output msg
String outMsg = "ok";
out.write(outMsg);
out.flush();
Log.i("TcpClient", "sent: " + outMsg);
//accept server response
String inMsg = null;
try {
inMsg = in.readLine() + System.getProperty("line.separator");
//Send ur data to the below method to do ur process
processdata(inMsg);
}
This my suggestion to use this code under the AsyncTask to support for further higher platform. if didnt done already..

Thank you very much... will give it a try shortly!

jacauc said:
Thank you very much... will give it a try shortly!
Click to expand...
Click to collapse
ok man, if u have problem with this code post it here and send PM.. Then only i can reach U immediately...

I'm particularly interested in how to convert these few particular lines of code to the UDP format..
The attached code sample is very close to what I came up with, but I'm not sure how to construct the packet and parse the results:
Code:
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddressOut);
and
Code:
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
and especially this line:
Code:
byte[] tempDataBuf = Arrays.copyOfRange(receiveData, 0, receivePacket.getLength());
Also...
What does this part do?:
Code:
System.getProperty("line.separator");
Any suggestions?
Thanks again

@jacauc
First of all if u are developing an Client application the following code will help U, For server coding its different its not Like UPD.
UDP probably need both server as all client socket to send and receive the data. But in case of TCP, its not necessary to have a Server Socket only client socket is enough for both read and write..
Code:
java.net.Socket s=new Socket(InetAddress.getByName(pre.getString("ip", "192.168.0.2")),2020);
Click to expand...
Click to collapse
This code create a client tcp socket and allow u to communication to the specific ip and port..
Code:
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddressOut);
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
Click to expand...
Click to collapse
these two lines will probably replaced by the above single line..
But if u for handling TCP socket U need two stream one for reading and other for write data to the stream.
Code:
java.io.InputStreamReader in = new BufferedReader(new InputStreamReader(s.getInputStream()));
java.io.OutputStreamWriter out= new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
Click to expand...
Click to collapse
The above two line probably help to construct Input and out Stream for u from that Socket.
byte[] tempDataBuf = Arrays.copyOfRange(receiveData, 0, receivePacket.getLength());
Click to expand...
Click to collapse
There is no necessary for this code here because u directly get the String of data from this stream
Code:
String inMsg = in.readLine()
;
Click to expand...
Click to collapse
This line will read the line of string from the stream.
System.getProperty("line.separator");
Click to expand...
Click to collapse
This line is not must. This line will add the system specific line sperator at the end of the string. Is used this in my application to find the line sperator to avoid some system related problem while finding the line end point..

@CoolMonster
Thanks again for your time... this is starting to make a lot of sense now!
I'm getting close!
One thing I had in the UDP code was to send a pre constructed byte to the Digi Wifi XBEE box i'm interfacing with. This is "senddata"
Now if I do
Code:
out.write(sendData);
I get an error message stating that out.write cannot handle a byte.
I have
Code:
private byte[] sendData = new byte[1024];
Does this mean that I should send my data in a string format instead of byte?

@CoolMonster
More information after some additional research:
Prior to sending my string to the hardware module, I need to send some packets to open the communication channel.
For the UDP packet, this is assembled as follows in Hex:
Command ID: 0x02
Command Options: 0
Frame ID: 0x01
Config Options: 0x02
AT Command: 49 53 (This is the HEX for the AT command I want to send, which translates to "IS" in ascii)
Thus, the packet looks like this in Hex:
02 00 01 02 49 53
Then I will get a Hex result which I am already parsing to make sense of the output.

@jacauc
http://stackoverflow.com/a/2879077/1405008
Click to expand...
Click to collapse
hai man check this link for handling byte array in tcp connection...
Let me know if u face problem in handling the above solution..
But I am sure about the Interface what u are using. U better test it by creating simple local server and test the code then test it with the real system..

Appreciate all your help with this! Seems to be working like I wanted it to now.
Thanks

jacauc said:
Appreciate all your help with this! Seems to be working like I wanted it to now.
Thanks
Click to expand...
Click to collapse
Cool, Ur welcome man...