I want to use MoveFile function, this function use two LPWSTR arguments, but I have one char* and LWSTR, how to concatenate them?
//move file
LPWSTR latestFile = L"test.SPL";
char* spoolFolder = "C:\\Windows\\System32\\spool\PRINTERS\\";
LPWSTR fileToMove = spoolFolder + latestFile;
BOOL moved = MoveFile(latestFile, L"C:\\UnprocessedFiles\\" + latestFile);
Just for clarification, LPWSTR is a typedef for wchar_t*. You can use wcscat_s to conctenate strings of this form. Your one char* string should just be changed to be of the same type, since you have it there as a simple literal (just prefix the literal with L and change the declared type). Since you tagged this as C++, however, you can do all of this more simply by using the std::wstring class.
std::wstring latestFile = wstring("test.SPL");
std::wstring spoolFolder = wstring("C:\\Windows\\System32\\spool\PRINTERS\\");
std::wstring fileToMove = spoolFolder + latestFile;
BOOL moved = MoveFile(latestFile.c_str(), fileToMove.c_str());
In deed, LPWSTR is just a typdef for w_char*. so if you consult MSDN you will see that:
typded wchar_t* LPWSTR;
here the w_char* means that your string will be encoded as UNICODE not ANSI scheme. So under windows a UNICODE string will be an UTF16 one ( 2 bytes for each char).
std::wstring is also a typedef for std::basic_string<wchar_t,char_traits<>> so by declaring your inputs as wstring and calling wasting.c_str() this will do the stuff.
Related
How can I convert a std::string to LPCSTR? Also, how can I convert a std::string to LPWSTR?
I am totally confused with these LPCSTR LPSTR LPWSTR and LPCWSTR.
Are LPWSTR and LPCWSTR the same?
Call c_str() to get a const char * (LPCSTR) from a std::string.
It's all in the name:
LPSTR - (long) pointer to string - char *
LPCSTR - (long) pointer to constant string - const char *
LPWSTR - (long) pointer to Unicode (wide) string - wchar_t *
LPCWSTR - (long) pointer to constant Unicode (wide) string - const wchar_t *
LPTSTR - (long) pointer to TCHAR (Unicode if UNICODE is defined, ANSI if not) string - TCHAR *
LPCTSTR - (long) pointer to constant TCHAR string - const TCHAR *
You can ignore the L (long) part of the names -- it's a holdover from 16-bit Windows.
str.c_str() gives you a const char *, which is an LPCSTR (Long Pointer to Constant STRing) -- means that it's a pointer to a 0 terminated string of characters. W means wide string (composed of wchar_t instead of char).
These are Microsoft defined typedefs which correspond to:
LPCSTR: pointer to null terminated const string of char
LPSTR: pointer to null terminated char string of char (often a buffer is passed and used as an 'output' param)
LPCWSTR: pointer to null terminated string of const wchar_t
LPWSTR: pointer to null terminated string of wchar_t (often a buffer is passed and used as an 'output' param)
To "convert" a std::string to a LPCSTR depends on the exact context but usually calling .c_str() is sufficient.
This works.
void TakesString(LPCSTR param);
void f(const std::string& param)
{
TakesString(param.c_str());
}
Note that you shouldn't attempt to do something like this.
LPCSTR GetString()
{
std::string tmp("temporary");
return tmp.c_str();
}
The buffer returned by .c_str() is owned by the std::string instance and will only be valid until the string is next modified or destroyed.
To convert a std::string to a LPWSTR is more complicated. Wanting an LPWSTR implies that you need a modifiable buffer and you also need to be sure that you understand what character encoding the std::string is using. If the std::string contains a string using the system default encoding (assuming windows, here), then you can find the length of the required wide character buffer and perform the transcoding using MultiByteToWideChar (a Win32 API function).
e.g.
void f(const std:string& instr)
{
// Assumes std::string is encoded in the current Windows ANSI codepage
int bufferlen = ::MultiByteToWideChar(CP_ACP, 0, instr.c_str(), instr.size(), NULL, 0);
if (bufferlen == 0)
{
// Something went wrong. Perhaps, check GetLastError() and log.
return;
}
// Allocate new LPWSTR - must deallocate it later
LPWSTR widestr = new WCHAR[bufferlen + 1];
::MultiByteToWideChar(CP_ACP, 0, instr.c_str(), instr.size(), widestr, bufferlen);
// Ensure wide string is null terminated
widestr[bufferlen] = 0;
// Do something with widestr
delete[] widestr;
}
Using LPWSTR you could change contents of string where it points to. Using LPCWSTR you couldn't change contents of string where it points to.
std::string s = SOME_STRING;
// get temporary LPSTR (not really safe)
LPSTR pst = &s[0];
// get temporary LPCSTR (pretty safe)
LPCSTR pcstr = s.c_str();
// convert to std::wstring
std::wstring ws;
ws.assign( s.begin(), s.end() );
// get temporary LPWSTR (not really safe)
LPWSTR pwst = &ws[0];
// get temporary LPCWSTR (pretty safe)
LPCWSTR pcwstr = ws.c_str();
LPWSTR is just a pointer to original string. You shouldn't return it from function using the sample above. To get not temporary LPWSTR you should made a copy of original string on the heap. Check the sample below:
LPWSTR ConvertToLPWSTR( const std::string& s )
{
LPWSTR ws = new wchar_t[s.size()+1]; // +1 for zero at the end
copy( s.begin(), s.end(), ws );
ws[s.size()] = 0; // zero at the end
return ws;
}
void f()
{
std::string s = SOME_STRING;
LPWSTR ws = ConvertToLPWSTR( s );
// some actions
delete[] ws; // caller responsible for deletion
}
The MultiByteToWideChar answer that Charles Bailey gave is the correct one. Because LPCWSTR is just a typedef for const WCHAR*, widestr in the example code there can be used wherever a LPWSTR is expected or where a LPCWSTR is expected.
One minor tweak would be to use std::vector<WCHAR> instead of a manually managed array:
// using vector, buffer is deallocated when function ends
std::vector<WCHAR> widestr(bufferlen + 1);
::MultiByteToWideChar(CP_ACP, 0, instr.c_str(), instr.size(), &widestr[0], bufferlen);
// Ensure wide string is null terminated
widestr[bufferlen] = 0;
// no need to delete; handled by vector
Also, if you need to work with wide strings to start with, you can use std::wstring instead of std::string. If you want to work with the Windows TCHAR type, you can use std::basic_string<TCHAR>. Converting from std::wstring to LPCWSTR or from std::basic_string<TCHAR> to LPCTSTR is just a matter of calling c_str. It's when you're changing between ANSI and UTF-16 characters that MultiByteToWideChar (and its inverse WideCharToMultiByte) comes into the picture.
Converting is simple:
std::string myString;
LPCSTR lpMyString = myString.c_str();
One thing to be careful of here is that c_str does not return a copy of myString, but just a pointer to the character string that std::string wraps. If you want/need a copy you'll need to make one yourself using strcpy.
The conversion is simple:
std::string str;
LPCSTR lpcstr = str.c_str();
The easiest way to convert a std::string to a LPWSTR is in my opinion:
Convert the std::string to a std::vector<wchar_t>
Take the address of the first wchar_t in the vector.
std::vector<wchar_t> has a templated ctor which will take two iterators, such as the std::string.begin() and .end() iterators. This will convert each char to a wchar_t, though. That's only valid if the std::string contains ASCII or Latin-1, due to the way Unicode values resemble Latin-1 values. If it contains CP1252 or characters from any other encoding, it's more complicated. You'll then need to convert the characters.
std::string myString("SomeValue");
LPSTR lpSTR = const_cast<char*>(myString.c_str());
myString is the input string and lpSTR is it's LPSTR equivalent.
How can I convert a std::string to LPCSTR? Also, how can I convert a std::string to LPWSTR?
I am totally confused with these LPCSTR LPSTR LPWSTR and LPCWSTR.
Are LPWSTR and LPCWSTR the same?
Call c_str() to get a const char * (LPCSTR) from a std::string.
It's all in the name:
LPSTR - (long) pointer to string - char *
LPCSTR - (long) pointer to constant string - const char *
LPWSTR - (long) pointer to Unicode (wide) string - wchar_t *
LPCWSTR - (long) pointer to constant Unicode (wide) string - const wchar_t *
LPTSTR - (long) pointer to TCHAR (Unicode if UNICODE is defined, ANSI if not) string - TCHAR *
LPCTSTR - (long) pointer to constant TCHAR string - const TCHAR *
You can ignore the L (long) part of the names -- it's a holdover from 16-bit Windows.
str.c_str() gives you a const char *, which is an LPCSTR (Long Pointer to Constant STRing) -- means that it's a pointer to a 0 terminated string of characters. W means wide string (composed of wchar_t instead of char).
These are Microsoft defined typedefs which correspond to:
LPCSTR: pointer to null terminated const string of char
LPSTR: pointer to null terminated char string of char (often a buffer is passed and used as an 'output' param)
LPCWSTR: pointer to null terminated string of const wchar_t
LPWSTR: pointer to null terminated string of wchar_t (often a buffer is passed and used as an 'output' param)
To "convert" a std::string to a LPCSTR depends on the exact context but usually calling .c_str() is sufficient.
This works.
void TakesString(LPCSTR param);
void f(const std::string& param)
{
TakesString(param.c_str());
}
Note that you shouldn't attempt to do something like this.
LPCSTR GetString()
{
std::string tmp("temporary");
return tmp.c_str();
}
The buffer returned by .c_str() is owned by the std::string instance and will only be valid until the string is next modified or destroyed.
To convert a std::string to a LPWSTR is more complicated. Wanting an LPWSTR implies that you need a modifiable buffer and you also need to be sure that you understand what character encoding the std::string is using. If the std::string contains a string using the system default encoding (assuming windows, here), then you can find the length of the required wide character buffer and perform the transcoding using MultiByteToWideChar (a Win32 API function).
e.g.
void f(const std:string& instr)
{
// Assumes std::string is encoded in the current Windows ANSI codepage
int bufferlen = ::MultiByteToWideChar(CP_ACP, 0, instr.c_str(), instr.size(), NULL, 0);
if (bufferlen == 0)
{
// Something went wrong. Perhaps, check GetLastError() and log.
return;
}
// Allocate new LPWSTR - must deallocate it later
LPWSTR widestr = new WCHAR[bufferlen + 1];
::MultiByteToWideChar(CP_ACP, 0, instr.c_str(), instr.size(), widestr, bufferlen);
// Ensure wide string is null terminated
widestr[bufferlen] = 0;
// Do something with widestr
delete[] widestr;
}
Using LPWSTR you could change contents of string where it points to. Using LPCWSTR you couldn't change contents of string where it points to.
std::string s = SOME_STRING;
// get temporary LPSTR (not really safe)
LPSTR pst = &s[0];
// get temporary LPCSTR (pretty safe)
LPCSTR pcstr = s.c_str();
// convert to std::wstring
std::wstring ws;
ws.assign( s.begin(), s.end() );
// get temporary LPWSTR (not really safe)
LPWSTR pwst = &ws[0];
// get temporary LPCWSTR (pretty safe)
LPCWSTR pcwstr = ws.c_str();
LPWSTR is just a pointer to original string. You shouldn't return it from function using the sample above. To get not temporary LPWSTR you should made a copy of original string on the heap. Check the sample below:
LPWSTR ConvertToLPWSTR( const std::string& s )
{
LPWSTR ws = new wchar_t[s.size()+1]; // +1 for zero at the end
copy( s.begin(), s.end(), ws );
ws[s.size()] = 0; // zero at the end
return ws;
}
void f()
{
std::string s = SOME_STRING;
LPWSTR ws = ConvertToLPWSTR( s );
// some actions
delete[] ws; // caller responsible for deletion
}
The MultiByteToWideChar answer that Charles Bailey gave is the correct one. Because LPCWSTR is just a typedef for const WCHAR*, widestr in the example code there can be used wherever a LPWSTR is expected or where a LPCWSTR is expected.
One minor tweak would be to use std::vector<WCHAR> instead of a manually managed array:
// using vector, buffer is deallocated when function ends
std::vector<WCHAR> widestr(bufferlen + 1);
::MultiByteToWideChar(CP_ACP, 0, instr.c_str(), instr.size(), &widestr[0], bufferlen);
// Ensure wide string is null terminated
widestr[bufferlen] = 0;
// no need to delete; handled by vector
Also, if you need to work with wide strings to start with, you can use std::wstring instead of std::string. If you want to work with the Windows TCHAR type, you can use std::basic_string<TCHAR>. Converting from std::wstring to LPCWSTR or from std::basic_string<TCHAR> to LPCTSTR is just a matter of calling c_str. It's when you're changing between ANSI and UTF-16 characters that MultiByteToWideChar (and its inverse WideCharToMultiByte) comes into the picture.
Converting is simple:
std::string myString;
LPCSTR lpMyString = myString.c_str();
One thing to be careful of here is that c_str does not return a copy of myString, but just a pointer to the character string that std::string wraps. If you want/need a copy you'll need to make one yourself using strcpy.
The conversion is simple:
std::string str;
LPCSTR lpcstr = str.c_str();
The easiest way to convert a std::string to a LPWSTR is in my opinion:
Convert the std::string to a std::vector<wchar_t>
Take the address of the first wchar_t in the vector.
std::vector<wchar_t> has a templated ctor which will take two iterators, such as the std::string.begin() and .end() iterators. This will convert each char to a wchar_t, though. That's only valid if the std::string contains ASCII or Latin-1, due to the way Unicode values resemble Latin-1 values. If it contains CP1252 or characters from any other encoding, it's more complicated. You'll then need to convert the characters.
std::string myString("SomeValue");
LPSTR lpSTR = const_cast<char*>(myString.c_str());
myString is the input string and lpSTR is it's LPSTR equivalent.
Is there any method?
My computer is AMD64.
::std::string str;
BOOL loadU(const wchar_t* lpszPathName, int flag = 0);
When I used:
loadU(&str);
the VS2005 compiler says:
Error 7 error C2664:: cannot convert parameter 1 from 'std::string *__w64 ' to 'const wchar_t *'
How can I do it?
First convert it to std::wstring:
std::wstring widestr = std::wstring(str.begin(), str.end());
Then get the C string:
const wchar_t* widecstr = widestr.c_str();
This only works for ASCII strings, but it will not work if the underlying string is UTF-8 encoded. Using a conversion routine like MultiByteToWideChar() ensures that this scenario is handled properly.
If you have a std::wstring object, you can call c_str() on it to get a wchar_t*:
std::wstring name( L"Steve Nash" );
const wchar_t* szName = name.c_str();
Since you are operating on a narrow string, however, you would first need to widen it. There are various options here; one is to use Windows' built-in MultiByteToWideChar routine. That will give you an LPWSTR, which is equivalent to wchar_t*.
You can use the ATL text conversion macros to convert a narrow (char) string to a wide (wchar_t) one. For example, to convert a std::string:
#include <atlconv.h>
...
std::string str = "Hello, world!";
CA2W pszWide(str.c_str());
loadU(pszWide);
You can also specify a code page, so if your std::string contains UTF-8 chars you can use:
CA2W pszWide(str.c_str(), CP_UTF8);
Very useful but Windows only.
If you are on Linux/Unix have a look at mbstowcs() and wcstombs() defined in GNU C (from ISO C 90).
mbs stand for "Multi Bytes String" and is basically the usual zero terminated C string.
wcs stand for Wide Char String and is an array of wchar_t.
For more background details on wide chars have a look at glibc documentation here.
Need to pass a wchar_t string to a function and first be able to create the string from a literal string concantenated with an integer variable.
The original string looks like this, where 4 is the physical drive number, but I want that to be changeable to match whatever drive number I want to pass to the function
auto TargetDrive = L"\\\\.\\PhysicalDrive4";
The following works
int a = 4;
std::string stddrivestring = "\\\\.\\PhysicalDrive" + to_string(a);
std::wstring widedrivestring = std::wstring(stddrivestring.begin(), stddrivestring.end());
const wchar_t* TargetDrive = widedrivestring.c_str();
How can I convert a std::string to LPCSTR? Also, how can I convert a std::string to LPWSTR?
I am totally confused with these LPCSTR LPSTR LPWSTR and LPCWSTR.
Are LPWSTR and LPCWSTR the same?
Call c_str() to get a const char * (LPCSTR) from a std::string.
It's all in the name:
LPSTR - (long) pointer to string - char *
LPCSTR - (long) pointer to constant string - const char *
LPWSTR - (long) pointer to Unicode (wide) string - wchar_t *
LPCWSTR - (long) pointer to constant Unicode (wide) string - const wchar_t *
LPTSTR - (long) pointer to TCHAR (Unicode if UNICODE is defined, ANSI if not) string - TCHAR *
LPCTSTR - (long) pointer to constant TCHAR string - const TCHAR *
You can ignore the L (long) part of the names -- it's a holdover from 16-bit Windows.
str.c_str() gives you a const char *, which is an LPCSTR (Long Pointer to Constant STRing) -- means that it's a pointer to a 0 terminated string of characters. W means wide string (composed of wchar_t instead of char).
These are Microsoft defined typedefs which correspond to:
LPCSTR: pointer to null terminated const string of char
LPSTR: pointer to null terminated char string of char (often a buffer is passed and used as an 'output' param)
LPCWSTR: pointer to null terminated string of const wchar_t
LPWSTR: pointer to null terminated string of wchar_t (often a buffer is passed and used as an 'output' param)
To "convert" a std::string to a LPCSTR depends on the exact context but usually calling .c_str() is sufficient.
This works.
void TakesString(LPCSTR param);
void f(const std::string& param)
{
TakesString(param.c_str());
}
Note that you shouldn't attempt to do something like this.
LPCSTR GetString()
{
std::string tmp("temporary");
return tmp.c_str();
}
The buffer returned by .c_str() is owned by the std::string instance and will only be valid until the string is next modified or destroyed.
To convert a std::string to a LPWSTR is more complicated. Wanting an LPWSTR implies that you need a modifiable buffer and you also need to be sure that you understand what character encoding the std::string is using. If the std::string contains a string using the system default encoding (assuming windows, here), then you can find the length of the required wide character buffer and perform the transcoding using MultiByteToWideChar (a Win32 API function).
e.g.
void f(const std:string& instr)
{
// Assumes std::string is encoded in the current Windows ANSI codepage
int bufferlen = ::MultiByteToWideChar(CP_ACP, 0, instr.c_str(), instr.size(), NULL, 0);
if (bufferlen == 0)
{
// Something went wrong. Perhaps, check GetLastError() and log.
return;
}
// Allocate new LPWSTR - must deallocate it later
LPWSTR widestr = new WCHAR[bufferlen + 1];
::MultiByteToWideChar(CP_ACP, 0, instr.c_str(), instr.size(), widestr, bufferlen);
// Ensure wide string is null terminated
widestr[bufferlen] = 0;
// Do something with widestr
delete[] widestr;
}
Using LPWSTR you could change contents of string where it points to. Using LPCWSTR you couldn't change contents of string where it points to.
std::string s = SOME_STRING;
// get temporary LPSTR (not really safe)
LPSTR pst = &s[0];
// get temporary LPCSTR (pretty safe)
LPCSTR pcstr = s.c_str();
// convert to std::wstring
std::wstring ws;
ws.assign( s.begin(), s.end() );
// get temporary LPWSTR (not really safe)
LPWSTR pwst = &ws[0];
// get temporary LPCWSTR (pretty safe)
LPCWSTR pcwstr = ws.c_str();
LPWSTR is just a pointer to original string. You shouldn't return it from function using the sample above. To get not temporary LPWSTR you should made a copy of original string on the heap. Check the sample below:
LPWSTR ConvertToLPWSTR( const std::string& s )
{
LPWSTR ws = new wchar_t[s.size()+1]; // +1 for zero at the end
copy( s.begin(), s.end(), ws );
ws[s.size()] = 0; // zero at the end
return ws;
}
void f()
{
std::string s = SOME_STRING;
LPWSTR ws = ConvertToLPWSTR( s );
// some actions
delete[] ws; // caller responsible for deletion
}
The MultiByteToWideChar answer that Charles Bailey gave is the correct one. Because LPCWSTR is just a typedef for const WCHAR*, widestr in the example code there can be used wherever a LPWSTR is expected or where a LPCWSTR is expected.
One minor tweak would be to use std::vector<WCHAR> instead of a manually managed array:
// using vector, buffer is deallocated when function ends
std::vector<WCHAR> widestr(bufferlen + 1);
::MultiByteToWideChar(CP_ACP, 0, instr.c_str(), instr.size(), &widestr[0], bufferlen);
// Ensure wide string is null terminated
widestr[bufferlen] = 0;
// no need to delete; handled by vector
Also, if you need to work with wide strings to start with, you can use std::wstring instead of std::string. If you want to work with the Windows TCHAR type, you can use std::basic_string<TCHAR>. Converting from std::wstring to LPCWSTR or from std::basic_string<TCHAR> to LPCTSTR is just a matter of calling c_str. It's when you're changing between ANSI and UTF-16 characters that MultiByteToWideChar (and its inverse WideCharToMultiByte) comes into the picture.
Converting is simple:
std::string myString;
LPCSTR lpMyString = myString.c_str();
One thing to be careful of here is that c_str does not return a copy of myString, but just a pointer to the character string that std::string wraps. If you want/need a copy you'll need to make one yourself using strcpy.
The conversion is simple:
std::string str;
LPCSTR lpcstr = str.c_str();
The easiest way to convert a std::string to a LPWSTR is in my opinion:
Convert the std::string to a std::vector<wchar_t>
Take the address of the first wchar_t in the vector.
std::vector<wchar_t> has a templated ctor which will take two iterators, such as the std::string.begin() and .end() iterators. This will convert each char to a wchar_t, though. That's only valid if the std::string contains ASCII or Latin-1, due to the way Unicode values resemble Latin-1 values. If it contains CP1252 or characters from any other encoding, it's more complicated. You'll then need to convert the characters.
std::string myString("SomeValue");
LPSTR lpSTR = const_cast<char*>(myString.c_str());
myString is the input string and lpSTR is it's LPSTR equivalent.
Is there any method?
My computer is AMD64.
::std::string str;
BOOL loadU(const wchar_t* lpszPathName, int flag = 0);
When I used:
loadU(&str);
the VS2005 compiler says:
Error 7 error C2664:: cannot convert parameter 1 from 'std::string *__w64 ' to 'const wchar_t *'
How can I do it?
First convert it to std::wstring:
std::wstring widestr = std::wstring(str.begin(), str.end());
Then get the C string:
const wchar_t* widecstr = widestr.c_str();
This only works for ASCII strings, but it will not work if the underlying string is UTF-8 encoded. Using a conversion routine like MultiByteToWideChar() ensures that this scenario is handled properly.
If you have a std::wstring object, you can call c_str() on it to get a wchar_t*:
std::wstring name( L"Steve Nash" );
const wchar_t* szName = name.c_str();
Since you are operating on a narrow string, however, you would first need to widen it. There are various options here; one is to use Windows' built-in MultiByteToWideChar routine. That will give you an LPWSTR, which is equivalent to wchar_t*.
You can use the ATL text conversion macros to convert a narrow (char) string to a wide (wchar_t) one. For example, to convert a std::string:
#include <atlconv.h>
...
std::string str = "Hello, world!";
CA2W pszWide(str.c_str());
loadU(pszWide);
You can also specify a code page, so if your std::string contains UTF-8 chars you can use:
CA2W pszWide(str.c_str(), CP_UTF8);
Very useful but Windows only.
If you are on Linux/Unix have a look at mbstowcs() and wcstombs() defined in GNU C (from ISO C 90).
mbs stand for "Multi Bytes String" and is basically the usual zero terminated C string.
wcs stand for Wide Char String and is an array of wchar_t.
For more background details on wide chars have a look at glibc documentation here.
Need to pass a wchar_t string to a function and first be able to create the string from a literal string concantenated with an integer variable.
The original string looks like this, where 4 is the physical drive number, but I want that to be changeable to match whatever drive number I want to pass to the function
auto TargetDrive = L"\\\\.\\PhysicalDrive4";
The following works
int a = 4;
std::string stddrivestring = "\\\\.\\PhysicalDrive" + to_string(a);
std::wstring widedrivestring = std::wstring(stddrivestring.begin(), stddrivestring.end());
const wchar_t* TargetDrive = widedrivestring.c_str();