cannot convert parameter 1 from 'char' to 'LPCWSTR'

Question

I keep getting this error: cannot convert parameter 1 from 'char' to 'LPCWSTR'

int main(int argc, char argv[])    
{

   // open port for I/O
   HANDLE h = CreateFile(argv[1],GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,0,NULL);

   if(h == INVALID_HANDLE_VALUE) {
       PrintError("E012_Failed to open port");

can someone help?

score 126 · Answer 1 · answered Oct 13 '10 at 14:58

126

Go to the Properties for your Project and under Configuration Properties/General, change the Character Set to "Not Set". This way, the compiler will not assume that you want Unicode characters, which are selected by default:

alt text

answered Oct 13 '10 at 14:58

Michael Goldshteyn

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Scouring around for hours till I found this thanks – JonoJames Aug 04 '22 at 09:49
Now under Configuration Properties / Advanced. – Skyfish Aug 07 '23 at 12:51

score 6 · Accepted Answer · answered Oct 13 '10 at 14:51

6

It should be

int main(int argc, char* argv[])

And

HANDLE h = CreateFileA(argv[1],GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,0,NULL);

answered Oct 13 '10 at 14:51

Yakov Galka

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4

I don't thing using the ANSI version of CreateFile is the right way to go, next thing you know and he'll start changing all the function calls to use the ANSI version. – Nikola Smiljanić Oct 13 '10 at 15:00
2

@Nikola: Of course it's the wrong way! I just think that it's not appropriate to explain the difference between char, wchat_t, TCHAR and how to write correct unicode applications to an absolute beginner. – Yakov Galka Oct 13 '10 at 15:04

score 5 · Answer 3 · answered Oct 13 '10 at 14:59

This is the main function that Visual Studio creates by default:

int _tmain(int argc, _TCHAR* argv[])

Where _TCHAR is defined to be char or wchar_t depending if _UNICODE is defined or not. The same thing happens with API functions. I would advise you against using explicit CreateFileA. Change your main and use CreateFile.

score 2 · Answer 4 · answered Oct 13 '10 at 15:08

Depending on your compiler setting for CharacterSet, you may need to perform a multibyte / widechar conversion, or change the CharacterSet if you don't care what it is.

For converting with MultiByteToWideChar, see the following...

http://www.codeguru.com/forum/showthread.php?t=231165

score 0 · Answer 5 · answered Oct 13 '10 at 14:54

I guess you're compiling with Unicode enabled. Then with char argv[], argv is a char array, so argv[1] is a char, and CreateFile wants a const wchar_t* as first parameter, not a char.

That said, your main definition is also broken, it should have char* argv[]. With that change, you can call CreateFileA.

cannot convert parameter 1 from 'char' to 'LPCWSTR'

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