How to translate char to tchar in win32

Question

2.33/5 (2 votes)

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When I try to compile below code under VS2012, can NOT success.
Error message is identifier "LtmpStr" is undefined, on last line.

C++

int point_num;
TCHAR szText;
char tmpStr[] = {'\0'};
point_num = 100;
sprintf(tmpStr, "%d", point_num);
szText = _T(tmpStr);

What I have tried:

I have try change szText to *szText, still can not work.

Posted 14-Dec-17 4:16am

flighta

Updated 15-Dec-17 1:31am

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Comments

Richard MacCutchan 14-Dec-17 11:24am

_T() is a macro used to generate string constants in either ANSI or Unicode. It is not a conversion function, so it will not work on character variables or arrays.

3 solutions

Solution 1

Take a look: c++ - How to convert char* to TCHAR[ ]? - Stack Overflow[^]

If you include the header file:

C++

#include "atlstr.h"

Then you can use the A2T macro as below:

// You'd need this line if using earlier versions of ATL/Visual Studio
// USES_CONVERSION;

char*  stheParameterFileName = argv[1];
TCHAR szName [512];
_tcscpy(szName, A2T(stheParameterFileName));
MessageBox(NULL, szName, szName, MB_OK);

Posted 14-Dec-17 4:22am

Leo Chapiro

Comments

flighta 15-Dec-17 7:00am

Thank you, but still can not work.

Solution 3

Finally I found the solution, thanks all!

C++

TCHAR szText[10]; 
	char tmpStr[10] = {'\0'};
	int tmp_point_num = 10;
	sprintf(tmpStr, "%d", tmp_point_num);
	size_t newsize = strlen(tmpStr) + 1;

	wchar_t * wcstring = new wchar_t[newsize];

	size_t convertedChars = 0;
	mbstowcs_s(&convertedChars, wcstring, newsize, tmpStr, _TRUNCATE);

of course, we need include

C++

<pre>#include <string>

#include "atlbase.h"
#include "atlstr.h"
#include "comutil.h"

Posted 15-Dec-17 1:31am

flighta

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CPallini · Accepted Answer · 2017-12-14T05:54:00

Solution 2

Quote:
char tmpStr[] = {'\0'};
point_num = 100;
sprintf(tmpStr, "%d", point_num);

That's the road to the disaster: your buffer is 1-character long, sprintf overruns it.

Use instead the C++ features, try, for instance:

C++

std::basic_ostringstream<TCHAR> its;
its << point_num;
std::basic_string<TCHAR> ts = its.str();
MessageBox(NULL,ts.c_str(),_T("INFO"), MB_ICONINFORMATION);

Posted 14-Dec-17 5:54am

CPallini

Comments

flighta 15-Dec-17 7:07am

Thank you.
I have change the code as below, but now have 3 error message.

#include "stdafx.h"
#include "atlstr.h"

TCHAR szText[10];
char tmpStr[10] = {'\0'};
int tmp_point_num = 10;
sprintf(tmpStr, "%d", tmp_point_num);
_tcscpy(szText, A2T(tmpStr));

error message:
error C2065: '_lpa': undeclared identifier
error C2065: '_convert': undeclared identifier
error C2065: '_acp': underclared identifier

Do I include more .h file???

CPallini 15-Dec-17 7:38am

You have to specify
USES_CONVERSION
see
https://msdn.microsoft.com/en-us/library/87zae4a3.aspx
(look at the bottom of the page)