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();
Related
hi ther i wonder if you could help me on this simple task. I'm creating a GPS application to run on the XDA2, i'm using eVC++ to do the implementation.
at the moment i'm reading the GPS signal via bluetooth over a virtual COM port, the signal coming from the GPS if a ASCII sinal and i'm duimping this into a char buffer.
However i need to convert this to UNICODE in order to display it on the Pocket PC, how's best to convert a buffer full of ASCII into Unicode so i may display it?
I tried using MultiByteToWideChar(), but it doesn't seem to work properly, maybe i haven't set it up correctly? Could someone point me in the right direction!
Below is an example of what i tried:
Code:
char buf[50]; // contains output from GPS
TCHAR Message[50]; //where i intended to put the message so i could display it
MultiByteToWideChar(CP_ACP, MB_PRECOMPOSED, buf, -1, Message, 0);
Thank in advance
I'm sure it's not the right way to go about it, but I generally wsprintf for short strings.
However, don't listen to me, I'm a mad man. Check this page out instead:
http://www.i18nguy.com/unicode/c-unicode.html
V
Thanks for that, out of curiosity, how would you use wsprintf to convert ASCII to unicode, i tried that before with no real success!
The last value passed to MultiByteToWideChar tells this function the size of the result buffer, Message in your case. You have passed zero, all that does is makes the function return the size of a TCHAR variable it needs to put the Ascii input buf into.
You need to put sizeof(Message) as the last parameter and not zero.
The other way (better way ?) of doing this is first you call the MultiByteToWideChar function with the zero parameter as you have and then you malloc the result * sizeof(TCHAR).
Thanks for the advise, after looking into the function more i realised this is where i was going wrong, and i have now managed to make the conversion. Thanks for pointing that out though!
Hi everybody
I tried to achieve a handle for readFile/writeFile operations using lineGetID.
The call to the function passed without errors. My problem is that the handle that I get is 0..., and I should make IO operations some how...
My code:
lRet := lineGetID( FLineHandle, 0, 0, LINECALLSELECT_LINE, PVarString, szClassType );
if lRet = 0 then
begin
FDevHandle := (LPHANDLE(PByte(PVarString) + PVarString^.dwStringOffset ))^;
// some more non relevant code which checks the validity of FDevHandle....
end;
The call to lineGetID is done after successful call to lineGetOpen. I test my application on i-mate jam with WM2003.
Thanks ahead
Kobi
I solved the problem
Hi everybody
For those who encounters the same problem as mine here is the solution that I finally found:
1. The Handle is NULL if we call the lineGetID using LINECALLSELECT_LINE. We should call lineGetID after getting into the LINECALLSTATE_CONNECTED state and use the LINECALLSTATE_CALL parameter. This information was found in the MSDN.
2. The lineGetID (as well as other line functions) doesn't report (I use TAPI 2.0 with WM-2003 on i-mate jam - the cellular line channel) the error LINEERR_STRUCTURETOOSMALL, so immediately after calling the lineGetID I added the following line (I use free pascal compiler):
if (Result = 0) and (PVarString^.dwTotalSize < PVarString^.dwNeededSize) then
Result := integer(LINEERR_STRUCTURETOOSMALL);
After this line comes the characteristic TAPI code which checks if either we should reallocate the previous block, or we can already use the data that call should have given to us.
Just after considering these 2 issues I got a vaild Handle...
Kobi
Hi Kobi,
I also having difficulties creating handle to write data on this TAPI Line, Can you please help me translate your code in VB.NET or C#, I am using VB and C# on developing application in WM2003.
Many thanks in Advance,
Eefendi
More complete code
Hi Eefendi
I neither know VB.NET nor C#, so it will be in Pascal, but I will add comments.
The code itself should be activated after you received the LINE_CALLSTATECONNECTED message/event (depends on the mechanism you selected when you called lineInitialize).
The CallHandle is a variable holds the handle of the call you want to achieve a handle to its stream (you achieve CallHandle, in incoming call for example, using LINE_CALLSTATEOFFERING message/event). The final result we want is stored in Handle. The line itself should be opened using "comm" or "comm/datamodem" class type.
var
VarSize,
Res : integer;
PVarString : LPVARSTRING;
szClassType : PWideChar = 'comm/datamodem';
// these variables definitions is equivalent to the following C code:
// int VarSize, Res;
// LPVARSTRING PVarString;
// TCHAR *szClassType = "comm/datamodem";
begin
VarSize := sizeof(VARSTRING);
Handle := 0;
repeat
GetMem( PVarString, VarSize ); // alloc VarSize bytes
PVarString^.TotalSize := VarSize;
Res := lineGetID( 0, 0, CallHandle, LINECALLSELECT_CALL, PVarString, szClassType );
if (Res = 0) and (PVarString^.TotalSize < PVarString^.NeededSize) then
Res := LINEERR_STRUCTURETOOSMALL;
if Res = LINEERR_STRUCTURETOOSMALL then
VarSize := PVarString^.NeededSize
else
if Res = 0 then // no error
Handle := LPHANDLE(PByte(PVarString) + PVarString^.dwStringOffset)^;
FreeMem( PVarString, PVarString^.TotalSize ); // free memory
until Res <> LINEERR_STRUCTURETOOSMALL; // finish the repeat until loop if this condition is TRUE
if (Handle <> 0) and (Handle <> INVALID_HANDLE_VALUE) then
//;use it as you wish....
end;
Some help to you for conversion:
1. PVarString^.TotalSize using C means PVarString->TotalSize
2. PByte using C means char*
3. type cast for example to PByte is done by PByte(...) while using C it is done by (PByte)...
4. Refering to a value which is referenced by the pointer P and storing it in variable X is done by "X := P^;". using C it is done by "X = *P;".
5. The operator <> means not equal. in C it is !=.
I hope it will be easy to you to translate it to C or any other language you want.
Good luck with your project.
Kobi
TAPI does seem to pop up a lot.
Have you looked at my code I posted a while back here ?
http://forum.xda-developers.com/viewtopic.php?t=18978
Hi Vangelderp and Kobi,
thanks for spending your time answering my questions and also thanks for the code provided. I use VB.Net 2003 on programming my pocket PC 2003, you guys provide me the code using pointer data type which is not supported in VB.net, so I am having trouble converting it. ( When I was learning C++, pointer is always make me confuse :roll: ). I wish you guys will be kind enough helping me convert it to VB.Net, just for small part to get Handle. :wink:
Mant Thanks in advance,
Eefendi
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
Hi Guys,
I'm going through the forum, I'm new to embedded developement, I've been able to do my first MessageBox("Hello World") in C using VS2005.
I want to understand how all this works, like :
- Accessing any "mass storage" device ? (the root FS ?, /, c:\, whatevername )
- Dumping the whole registry + values.
- Logging Process and activity even while "device locked" (new process, etc..)
And having more knownledge about the internals and devices, booting etc..
I'm kind of lost and my embedded knowledge is very thin..
The PPC i have is running WM5 on QTEK9100 (SPVM3000)..
Any pointers, posts, sources, small explication are more than welcome...
Hope you can help,
Regards,
r.
Welcome!
Wow those sure are some heavy requests for someone who is just starting.
How much experience do you have with C and Win32 APIs?
To start you off here is an excellent site for Windows Mobile programming tips and tricks:
www.pocketpcdn.com
Couple more pointers:
Device root is "\", no drives (SD cards mounted as folders) kind of like Linux.
All path are absolute - no ".\" or ".."
You can use standard C or Win32 functions for file operations.
Registry functions are also same as Desktop windows except you have to use the "Ex" version of of the function.
Example:
RegOpenKey - not implemented, use RegOpenKeyEx.
For process lists etc, google for ToolHelp32.
Thanks,
I'm at ease w/ ANSI C, have some familiarity w/ Win32 APIs,
but as far as I'm seeing I'm trying to code on Win32 Intel First,
then i try to "port" it to PocketPC Mobile, sometime it works
sometime functions doesn't even exists... MSDN doesn't seems very consistent over Win32 vs WM, but as I'm new I guess i'm missing a lot..
WinMain() prototype changes according to your target...otherwise
VS2005 yell about Overloading WinMain, It is VERY annnoying..anyway
Thanks for the links and the *Ex trick, I'll try to get deeper with this.
I have a strange problem trying to do my Own MessageBoxPrintf:
int MessageBoxPrintf(int, const char * title, const char * fmt, ...)
{
va_list ap;
char * buffer = NULL;
/* formatting and fixed size yes...*/
buffer = (char *) malloc (1024 * sizeof(char));
if (!buffer)
return -1;
memset(buffer, 0, 1024);
va_start(ap, fmt);
vsprintf(buffer, fmt, ap);
va_end(ap);
MessageBox(NULL, (LPCWSTR)buffer, (LPCWSTR)title, type);
return 0;
}
It does compile, but it display craps, since there is no stderr,stdout,stdin and
that I'm mostly coding on Win32/VMware, I don't know how to debug on my PPC (no USB connection), and I have no idea what's wrong.. it might be obvious, but it's late..
As I don't know what LPCWSTR stand for, I assumed char * and it did work on Win32 (XP) without hassle (except LPCWSTR types which are wrong for Win32 Target), so why it doesn't on WM5... is a mystery for me now..
Hope to be on speed ASAP to be able to release some stuff..
Thanks for your help,
Cheers,
r.
all WinAPI function on Pocket PC works with Unicode strings. So you have to convert from ANSI to Unicode.
ok, does the TEXT() macros convert to Unicode string, it seems not.
How to convert from ANSI to Unicode ?
you can work directly with wchar_t or use tchar that can be ansi or unicode, otherwise look for MultiByteToWideChar or CString object _T and TEXT Macro aren't for converting ansi but they makes unicode prefix strings... for example MessageBox(hWnd,_T("Hello World"),_T("my messagebox"),MB_OK);
I hope this help and don't forget MSDN have all replies
have fun,
Guybrush
ok it works! thanks!
just another question, how to dump the "disk" or how those devices are booting ROM?/Flash?
Currently I'm copying all the files from / to the SD card mount point is there anything else?
again thanks for your help.
++
r.
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...