How to put a CString variable in a message box?

Question

In my program, I need put a CString variable in a MessageBox. I use the following code:

messagebox("hi" + txt);

But I get the following error message:

error C2678: binary '+' : no operator found which takes a left-hand operand of type 'const char [3]' (or there is no acceptable conversion)

The error message is quite clear as to what the problem is. Did you read it? What have you tried? — Cody Gray - on strike, May 22 '14 at 08:29
What is the type of `txt` ? If it is `CString` and your project is an unicode project, then you probably must write `messagebox(L"hi" + txt);` — Jabberwocky, May 22 '14 at 08:54

score 0 · Answer 1 · answered May 22 '14 at 08:31

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Use format method of the CString. The Format method do thing like how printf, sprintf works.

Example

 CString str ;
 str.Format("Hi %s", txt);

answered May 22 '14 at 08:31

Sivaraman

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Error 1 error C2664: 'void ATL::CStringT::Format(const wchar_t *,...)' : cannot convert parameter 1 from 'const char [6]' to 'const wchar_t *' e:\project\visual studio 2008\projects\test2\test2\test2dlg.cpp 174 test2 – Ehsan Banaei May 22 '14 at 08:36
Unnecessary, you can concatenate two CString values using the binary `+` operator. You don't need Format unless you're actually doing some complex formatting. Either way, though, you will need to use wide string literals. Prefix them with an `L`. – Cody Gray - on strike May 22 '14 at 08:37
plz put your code @CodyGray – Ehsan Banaei May 22 '14 at 08:39
Cody Gray says you can use binary + with CString itself. That is CString str = _T("Hi ") + txt. @Cody Gray: When should I use L or _T? – Sivaraman May 22 '14 at 08:47
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Prefixing with `L` makes it a wide string. Using the `_T` macro determines at compile-time, based on some preprocessor definitions, whether the literal should be a wide or narrow string. Either one is fine, but `_T` is sort of pointless now since everything is Unicode. No one cross-compiles for ANSI or MBCS. – Cody Gray - on strike May 22 '14 at 08:49

score 0 · Accepted Answer · answered May 22 '14 at 08:41

0

you can use a CString variable to format, then pass it to MessageBox.
_T() is a macro for Unicode or MBCS.
you should make sure txt is same encode as str,

CString str ;
str.Format(_T("Hi %s"), txt);

answered May 22 '14 at 08:41

Jerry YY Rain

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score 0 · Answer 3 · answered May 22 '14 at 08:44

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Use the _T macro to wrap the string literal into a CString:

messagebox(_T("hi") + txt);

answered May 22 '14 at 08:44

Shoe

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How to put a CString variable in a message box?

3 Answers3