I'm trying the following code:
int length = SendMessage(textBoxPathToSource, WM_GETTEXTLENGTH, 0, 0);
LPCWSTR lpstr;
SendMessage(textBoxPathToSource, WM_GETTEXT, length+1, LPARAM(LPCWSTR));
std::string s(lpstr);
But it doesn't work.
You're using it absolutely incorrectly:
First, you are passing a type instead of a value here:
SendMessage(textBoxPathToSource, WM_GETTEXT, length+1, LPARAM(LPCWSTR));
Interfacing WinAPI functions who write to a string requires a buffer, since std::string's cannot be written to directly.
You need to define a space to hold the value:
WCHAR wszBuff[256] = {0}; (of course you could allocate the storage space using new, which you didn't, you just declared LPCWSTR lpstr).
Extract the string and store in that buffer:
SendMessage(textBoxPathToSource, WM_GETTEXT, 256, (LPARAM)wszBuff);
and perform std::wstring s(lpStr).
EDIT:
Please note the use of std::wstring, not std::string.
What ALevy said is correct, but it'd be better to use a std::vector<WCHAR> than a fixed-size buffer (or using new):
std::wstring s;
int length = SendMessageW(textBoxPathToSource, WM_GETTEXTLENGTH, 0, 0);
if (length > 0)
{
std::vector<WCHAR> buf(length + 1 /* NUL */);
SendMessageW(textBoxPathToSource,
WM_GETTEXT,
buf.size(),
reinterpret_cast<LPCWSTR>(&buf[0]));
s = &buf[0];
}
Related
I'm having a bit of trouble with handling unicode conversions.
The following code outputs this into my text file.
HELLO??O
std::string test = "HELLO";
std::string output;
int len = WideCharToMultiByte(CP_OEMCP, 0, (LPCWSTR)test.c_str(), -1, NULL, 0, NULL, NULL);
char *buf = new char[len];
int len2 = WideCharToMultiByte(CP_OEMCP, 0, (LPCWSTR)test.c_str(), -1, buf, len, NULL, NULL);
output = buf;
std::wofstream outfile5("C:\\temp\\log11.txt");
outfile5 << test.c_str();
outfile5 << output.c_str();
outfile5.close();
But as you can see, output is just a unicode conversion from the test variable. How is this possible?
Check if the LEN is correct after first measuring call. In general, you should not cast test.c_str() to LPCWSTR. The 'test' as is 'char'-string not 'wchar_t'-wstring. You may cast it to LPCSTR - note the 'W' missing. The WinAPI has distinction between that. You really should be using wstring if you want to keep widechars in it.. Yeah, after re-reading your code, the test should be a wstring, then you can cast it to LPCWSTR safely.
after reading this
Microsoft wstring reference
I changed
std::string test = "HELLO";
to
std::wstring test = L"HELLO";
And the string was outputted correctly and I got
HELLOHELLO
I am implementing a custom action for a WindowsCE CAB file, and I need to concat a LPCTSTR to get a proper path to an exe.
My custom action receives a LPCTSTR as an argument.
So (pseudocode):
extern "C" codeINSTALL_EXIT MYCUSTOMACTION_API Install_Exit(
HWND hwndParent,
LPCTSTR pszInstallDir,
WORD cFailedDirs,
WORD cFailedFiles,
WORD cFailedRegKeys,
WORD cFailedRegVals,
WORD cFailedShortcuts
)
{
if (FALSE == LaunchApp(pszInstallDir + "\\MyApp.exe"))
::MessageBox(hwndParent, L"Could not launch app!", L"Setup", MB_ICONINFORMATION );
return codeINSTALL_EXIT_DONE;
}
This is using the imaginary "+" operator, that I would use in my standard language, C#.
I have relatively little experience in C++. What is the proper way to append a LPCTSTR for my purposes? The LaunchApp method uses this type as an argument.
Also if I want to display the resulting path (for debugging purposes) in a MessageBox, is there a quick way to convert to a LPCWSTR?
For concatenation use StringCchCat
TCHAR pszDest[260] = _T("");
StringCchCat(pszDest, 260, pszInstallDir);
StringCchCat(pszDest, 260, _T("\\MyApp.exe"));
LaunchApp(pszDest);
You need to allocate a new buffer to assemble the combined string in and then copy both parts into it. You can either pick a fixed, large buffer size
TCHAR fullPath[MAX_PATH + 11]; // 11 = length of "\MyApp.exe" + nul in characters
_sntprintf_s(fullPath, MAX_PATH + 11, _T("%s\\MyApp.exe"), pszInstallDir);
or allocate it dynamically to fit:
size_t installDirLen = tcslen(pszInstallDir);
size_t bufferLen = installDirLen + 11; // again 11 = len of your string
LPWSTR fullPath = new TCHAR[bufferLen];
// if you're paranoid, check allocation succeeded: fullPath != null
tcsncpy_s(fullPath, bufferLen, pszInstallDir);
tcsncat_s(fullPath, bufferLen, _T"\\MyApp.exe");
// use it
delete fullPath;
If you're in Unicode mode then LPCTSTR == LPCWSTR (in MBCS mode == LPCSTR instead). Either way the MessageBox macro should work for you - it'll choose between MessageBoxA or MessageBoxW as appropriate.
As ctacke points out below, this in on Windows CE and I can't assume you're going to have the _s functions. I think in the second case it's OK to use the non _s variants since we know the buffer is big enough, but in the first _sntprintf does not guarantee a trailing null on the output string (as the _s version does) and so we need to initialise the buffer ourselves first:
size_t bufferLen = MAX_PATH + 11;
TCHAR fullPath[bufferLen];
// zero the buffer out first
memset(fullPath, 0, sizeof(TCHAR) * bufferLen);
// only write up to bufferLen - 1, i.e. ensure the last character is left zero
_sntprintf(fullPath, bufferLen - 1, _T("%s\\MyApp.exe"), pszInstallDir);
(It might also be possible to do this by omitting the memset and using _sntprintf's return value to find the end of the combined generated string and nul the next character.)
AFAICR Windows CE is Unicode only and so LPCTSTR == LPCWSTR always.
You can use string to be concatenated and then cast the result to LPCTSTR using ATL helpers like CA2T:
std::string filePath = "\\\\user\\Home\\";
std::string fileName = "file.ex";
std::string fullPath = filePath + fileName;
CA2T t(fullPath.c_str());
LPCTSTR lpctsrFullPath = t;
I am trying to convert a char string to a wchar string.
In more detail: I am trying to convert a char[] to a wchar[] first and then append " 1" to that string and the print it.
char src[256] = "c:\\user";
wchar_t temp_src[256];
mbtowc(temp_src, src, 256);
wchar_t path[256];
StringCbPrintf(path, 256, _T("%s 1"), temp_src);
wcout << path;
But it prints just c
Is this the right way to convert from char to wchar? I have come to know of another way since. But I'd like to know why the above code works the way it does?
mbtowc converts only a single character. Did you mean to use mbstowcs?
Typically you call this function twice; the first to obtain the required buffer size, and the second to actually convert it:
#include <cstdlib> // for mbstowcs
const char* mbs = "c:\\user";
size_t requiredSize = ::mbstowcs(NULL, mbs, 0);
wchar_t* wcs = new wchar_t[requiredSize + 1];
if(::mbstowcs(wcs, mbs, requiredSize + 1) != (size_t)(-1))
{
// Do what's needed with the wcs string
}
delete[] wcs;
If you rather use mbstowcs_s (because of deprecation warnings), then do this:
#include <cstdlib> // also for mbstowcs_s
const char* mbs = "c:\\user";
size_t requiredSize = 0;
::mbstowcs_s(&requiredSize, NULL, 0, mbs, 0);
wchar_t* wcs = new wchar_t[requiredSize + 1];
::mbstowcs_s(&requiredSize, wcs, requiredSize + 1, mbs, requiredSize);
if(requiredSize != 0)
{
// Do what's needed with the wcs string
}
delete[] wcs;
Make sure you take care of locale issues via setlocale() or using the versions of mbstowcs() (such as mbstowcs_l() or mbstowcs_s_l()) that takes a locale argument.
why are you using C code, and why not write it in a more portable way, for example what I would do here is use the STL!
std::string src = std::string("C:\\user") +
std::string(" 1");
std::wstring dne = std::wstring(src.begin(), src.end());
wcout << dne;
it's so simple it's easy :D
L"Hello World"
the prefix L in front of the string makes it a wide char string.
I'm trying to load into string the content of file saved on the dics. The file is .CS code, created in VisualStudio so I suppose it's saved in UTF-8 coding. I'm doing this:
FILE *fConnect = _wfopen(connectFilePath, _T("r,ccs=UTF-8"));
if (!fConnect)
return;
fseek(fConnect, 0, SEEK_END);
lSize = ftell(fConnect);
rewind(fConnect);
LPTSTR lpContent = (LPTSTR)malloc(sizeof(TCHAR) * lSize + 1);
fread(lpContent, sizeof(TCHAR), lSize, fConnect);
But result is so strange - the first part (half of the string is content of .CS file), then strange symbols like 췍췍췍췍췍췍췍췍췍췍췍췍췍췍췍췍췍췍췍췍췍췍췍 appear.
So I think I read the content in a wrong way. But how to do that properly?
Thank you so much and I'm looking to hear!
ftell(), fseek(), and fread() all operate on bytes, not on characters. In a Unicode environment, TCHAR is at least 2 bytes, so you are allocating and reading twice as much memory as you should be.
I have never seen fopen() or _wfopen() support a "ccs" attribute. You should use "rb" as the reading mode, read the raw bytes into memory, and then decode them once you have them all available, ie:
FILE *fConnect = _wfopen(connectFilePath, _T("rb"));
if (!fConnect)
return;
fseek(fConnect, 0, SEEK_END);
lSize = ftell(fConnect);
rewind(fConnect);
LPBYTE lpContent = (LPBYTE) malloc(lSize);
fread(lpContent, 1, lSize, fConnect);
fclose(lpContent);
.. decode lpContent as needed ...
free(lpContent);
Does the string contain all the contents of the cs file and then additional funny characters? Probably it's just not correctly null-terminated since fread will not automatically do that. You need to set the character following the string content to zero:
lpContent[lSize] = 0;
.. decode lpContent as needed ...
s2ws function convert string to wstring
std::wstring s2ws(const std::string& str)
{
int size_needed = MultiByteToWideChar(CP_UTF8, 0, &str[0], (int)str.size(), NULL, 0);
std::wstring wstrTo(size_needed, 0);
MultiByteToWideChar(CP_UTF8, 0, &str[0], (int)str.size(), &wstrTo[0], size_needed);
return wstrTo;
}
add null terminator in the end of buffer:
lpContent[lSize-1] = 0;
initialize wstring from buffer content
std::wstring replyStr = (s2ws((char*)lpContent));
I'm making a firefox extension (nsACString is from mozilla) but LoadLibrary expects a LPCWSTR. I googled a few options but nothing worked. Sort of out of my depth with strings so any references would also be appreciated.
It depends whether your nsACString (which I'll call str) holds ASCII or UTF-8 data:
ASCII
std::vector<WCHAR> wide(str.Length()+1);
std::copy(str.beginReading(), str.endReading(), wide.begin());
// I don't know whether nsACString has a terminating NUL, best to be sure
wide[str.Length()] = 0;
LPCWSTR newstr = &wide[0];
UTF-8
// get length, including nul terminator
int len = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS,
str.BeginReading(), str.Length(), 0, 0);
if (len == 0) panic(); // happens if input data is invalid UTF-8
// allocate enough space
std::vector<WCHAR> wide(len);
// convert string
MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS,
str.BeginReading(), str.Length(), &wide[0], len)
LPCWSTR newstr = &wide[0];
This allocates only as much space as is needed - if you want faster code that potentially uses more memory than necessary, you can replace the first two lines with:
int len = str.Length() + 1;
This works because a conversion from UTF-8 to WCHAR never results in more characters than there were bytes of input.
Firstly note: LoadLibrary need not accept a LPWSTR. Only LoadLibraryW does. You may call LoadLibraryA directly (passing a narrow LPCSTR) and it will perform the translation for you.
If you choose to do it yourself however, below is one possible example.
nsACString sFoo = ...; // Some string.
size_t len = sFoo.Length() + 1;
WCHAR *swFoo = new WCHAR[len];
MultiByteToWideChar(CP_ACP, 0, sFoo.BeginReading(), len - 1, swFoo, len);
swFoo[len - 1] = 0; // Null-terminate it.
...
delete [] swFoo;
nsACString a;
const char* pData;
PRUint32 iLen = NS_CStringGetData(a, &pData);