system("app.exe") also loads cmd.exe

[Zoefschildpad]

Like the TT says, I make a system call to run another program, but it also loads cmd.exe for some reason, is there anyway to make it not do that? it's really annoying.

the program I'm calling is made using the windows api as a WS_POPUP style if that matters.

[Moschops]

That's how system works. It's what it does. It opens a shell (i.e. cmd.exe)

If you want to start some other process, use the OS API. For example, under windows, CreateProcess

[Zoefschildpad]

Ah ok, that makes sense I guess.

I'm looking at CreateProcess atm, but it won't accept a string as the second argument and it wants a wchar* instead, how do I turn simple text into that data type?

[Computergeek01]

It should work fine with a string if you use the c_str() member function from the string class: http://www.cplusplus.com/reference/string/string/c_str/

[Zoefschildpad]

that didn't work (unless I messed up somehow but i don't think so)

        STARTUPINFO          si = { sizeof(si) };
        PROCESS_INFORMATION  pi;
        char * cstr, *p;

          string str ("monocle.exe");

          cstr = new char [str.size()+1];
          strcpy (cstr, str.c_str());

        if(CreateProcess(0, cstr, 0, 0, FALSE, 0, 0, 0, &si, &pi))
        {
        // optionally wait for process to finish
        WaitForSingleObject(pi.hProcess, INFINITE);


        CloseHandle(pi.hProcess);
        CloseHandle(pi.hThread);

that's my code and I get the following error:
error: cannot convert 'char*' to 'WCHAR*' for argument '2' to 'BOOL CreateProcessW(const WCHAR*, WCHAR*, _SECURITY_ATTRIBUTES*, _SECURITY_ATTRIBUTES*, BOOL, DWORD, void*, const WCHAR*, _STARTUPINFOW*, _PROCESS_INFORMATION*)'

I'm coding and compiling in QT Creator if that makes a difference

[Computergeek01]

I had it wrong. I normally just dereference the first character in the string, in your case it would look like this CreateProcess(0, &str[0], 0, 0, FALSE, 0, 0, 0, &si, &pi)

[Zoefschildpad]

same error, thanks for playing though. same result with &cstr[0]

[Computergeek01]

Well then you're doing something wrong. I just compiled it and it works.

[Zoefschildpad]

That's really strange, I changed it to the following as per your suggestion and I still get that error.

        STARTUPINFO          si = { sizeof(si) };
        PROCESS_INFORMATION  pi;
        char * cstr, *p;

          string str ("monocle.exe");

          cstr = new char [str.size()+1];
          strcpy (cstr, str.c_str());

          if(CreateProcess(0, &str[0], 0, 0, FALSE, 0, 0, 0, &si, &pi))
        {
        // optionally wait for process to finish
        WaitForSingleObject(pi.hProcess, INFINITE);


        CloseHandle(pi.hProcess);
        CloseHandle(pi.hThread);

[Zoefschildpad]

I fixed it. for future reference:

        STARTUPINFO          si = { sizeof(si) };
        PROCESS_INFORMATION  pi;
        char * cstr, *p;

        wstring str = (L"monocle.exe");//wstring type and the L to convert the string to wstring.

        if(CreateProcess(0, &str[0], 0, 0, FALSE, 0, 0, 0, &si, &pi))
        {
        // optionally wait for process to finish
        WaitForSingleObject(pi.hProcess, INFINITE);


        CloseHandle(pi.hProcess);
        CloseHandle(pi.hThread);

[webJose]

Yes, this is the good old "I mix WinAPI names with string data types without caring about their actual signatures".

1. If you use wide strings, you MUST call the WinAPI functions using their -W names. In your case, CreateProcessW().
2. If you use narrow (normal) strings, you MUST call the WinAPI functions using there -A names. In your case, CreateProcessA().
3. If you use the WinAPI names without any suffix (CreateProcess() in your case), you MUST use a data type that changes depending on the UNICODE #define:

typedef std::basic_string<TCHAR> tstring;

tstring str = TEXT("monocle.exe");
if (CreateProcess(0, &str[0], .....)