How to convert string to LPWSTR in c++ - c++

Question

Can anyone help in converting string to LPWSTR
string command=obj.getInstallationPath()+"<some string appended>"
Now i wat to pass it as parameter for CreateProcessW(xx,command,x...)
But createProcessW() accepts only LPWSTR so i need to cast string to LPWSTR
Thanks in Advance

Answer 1

If you have an ANSI string, then have you considered calling CreateProcessA instead? If there is a specific reason you need to call CreateProcessW then you will need to convert the string. Try the MultiByteToWideChar function.

Answer 2

Another way:
mbstowcs_s
use with string.c_str(), you can find example here or here
OR
USES_CONVERSION_EX;
std::string text = "text";
LPWSTR lp = A2W_EX(text.c_str(), text.length());
OR
{
std::string str = "String to LPWSTR";
BSTR b = _com_util::ConvertStringToBSTR(str.c_str());
LPWSTR lp = b;
Use lp before SysFreeString...
SysFreeString(b);
}

Answer 3

The easiest way to convert an ansi string to a wide (unicode) string is to use the string conversion macros.
To use these, put USES_CONVERSION at the top of your function, then you can use macros like A2W() to perform the conversion very easily.
eg.
char* sz = "tadaaa";
CreateProcessW(A2W(sz), ...);
The macros allocate space on the stack, perform the conversion and return the converted string.

Answer 4

Also, you might want to consider using TCHAR throughout... If I'm correct, the idea would be something like this:
typedef std::basic_string<TCHAR> tstring
// Make any methods you control return tstring values. Thus, you could write:
tstring command = obj.getInstallationPath();
CreateProcess(x, command.c_str(), ...);
Note that we use CreateProcess instead of CreateProcessW or CreateProcessA. The idea is that if UNICODE is defined, then TCHAR is typedefed to WCHAR and CreateProcess is #defined to be CreateProcessW, which accepts a LPWSTR; but if UNICODE is not defined, then TCHAR becomes char, and CreateProcess becomes CreateProcessA, which accepts a LPSTR. But I might not have the details right here... this stuff seems somewhat needlessly complicated :(.

Answer 5

Here is another option. I've been using this function to do the conversion.
//C++ string to WINDOWS UNICODE string
std::wstring s2ws(const std::string& s)
{
int len;
int slength = (int)s.length() + 1;
len = MultiByteToWideChar(CP_ACP, 0, s.c_str(), slength, 0, 0);
wchar_t* buf = new wchar_t[len];
MultiByteToWideChar(CP_ACP, 0, s.c_str(), slength, buf, len);
std::wstring r(buf);
delete[] buf;
return r;
}
And wrap your string like this.
s2ws( volume.c_str())