Question

I have been spending 2 hours trying to get my path string read from a .ini file to work with the CreateProcess function, which expects a LPCWSTR. For some reason, no matter how I do it, it just will not work.

I have the following code, which I’ve taken from another SO answer, and amended for my use, however CreateProcess still doesn’t start the process.

Can anybody help?

std::ifstream file(file_path.c_str());
    settings new_settings;
    if(file.is_open() && !file.fail())
    {

    std::string key;
    char sign = '=';
    std::string value;
    std::string line;

    while(!file.eof())
    {
        std::getline(file, key, sign);
        std::getline(file, value);

        //fill in settings struct with `value` variable.  Struct contains only `std::string` types.
    }
}

file.close();



    PROCESS_INFORMATION proc_info;      
    STARTUPINFO start_info;     
    memset(&start_info, 0, sizeof(start_info)); 
    start_info->cb = sizeof(STARTUPINFO);   

   std::string path = "C:\\Mydir\\myexe.exe";

    int len;

int slength = (int)path.length() + 1;
len = MultiByteToWideChar(CP_ACP, 0, path.c_str(), slength, 0, 0); 
wchar_t* buf = new wchar_t[len];
MultiByteToWideChar(CP_ACP, 0, path.c_str(), slength, buf, len);
std::wstring wpath(buf);
delete[] buf;

LPCWSTR p_path = wpath.c_str();

created = CreateProcess(p_path, lpPort, 0,0, FALSE, CREATE_NEW_CONSOLE,NULL,NULL,&start_info ,&proc_info);

DWORD dwErr = GetLastError();  //Returns 0x7b (Invalid Path Or FileName)

Answer 1

wchar_t* buf = new wchar_t[len];
MultiByteToWideChar(CP_ACP, 0, path.c_str(), slength, buf, len);
std::wstring wpath(buf);
delete[] buf;

I’m fairly sure this is incorrect. You should resize the wstring and use that buffer instead.

std::wstring wpath;
wpath.resize(len);
MultiByteToWideChar(CP_ACP, 0, path.c_str(), slength, &wpath[0], len);
CreateProcess(wpath.c_str(), ...