first chance exception when i use messagebox

Question

Whenever i use MessageBox function, i am getting first chance exception. My messagebox is like this.

MessageBox(NULL, (LPCWSTR)L"testing", (LPCWSTR)L"SOFTSAFETY", MB_OKCANCEL | MB_ICONWARNING);

If i debug, i am getting this

First-chance exception at 0x76267A24 (user32.dll) in Thread Message BOX.exe: 0xC0000005: Access violation reading location 0x001629D0.

First-chance exception at 0x76267A24 (user32.dll) in Thread Message BOX.exe: 0xC0000005: Access violation reading location 0x001629D0.

First-chance exception at 0x76267A24 (user32.dll) in Thread Message BOX.exe: 0xC0000005: Access violation reading location 0x001629D0.

First-chance exception at 0x76267A24 (user32.dll) in Thread Message BOX.exe: 0xC0000005: Access violation reading location 0x001629D0.

How can i remove those exceptions? My program is not suspended because of this exceptions, its just displaying in the output window. So can i neglect these. Please guide me.

What are those casts to `LPCWSTR` for? Something is badly wrong if you need those casts for the code to compile... — Cody Gray - on strike, May 22 '14 at 09:02
@CodyGray i need those casts, if i need to display string variables. — Kumar, May 22 '14 at 09:08
No, you don't. If you have to cast here, you are doing it wrong. The compiler was trying to tell you that, but you told it to shut up by adding casts. — Cody Gray - on strike, May 22 '14 at 09:08
Set the debugger to break on first chance exceptions if you want to see why they are happening. — Raymond Chen, May 24 '14 at 04:19

score 1 · Accepted Answer · edited May 24 '14 at 03:24

1

Perhaps taking a look on the MSDN would help you? The MessageBox function has the following prototype:

int WINAPI MessageBox(
  _In_opt_  HWND hWnd,
  _In_opt_  LPCTSTR lpText,
  _In_opt_  LPCTSTR lpCaption,
  _In_      UINT uType
);

LPCTSTR is a pointer to TCHAR, and that is not necessarily a wide character. In wtypes.h, you will find:

const TCHAR *LPCTSTR

and TCHAR can be wchar_t or a char, depending on your project's settings. Your problem is almost certainly that you forced (via a cast) wide chars where regular ones were expected.

You can try using the _T() macro, to generate regular or wide string literals according to your project's configuration.

edited May 24 '14 at 03:24

Cody Gray - on strike

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answered May 23 '14 at 10:54

user2511124

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All good advice, but don't neglect to point out that narrow ('regular') characters went obsolete for Windows programming over a decade ago. Anymore, *all* projects should have `UNICODE` and `_UNICODE` symbols defined to force everything to be wide characters. And lots of people go one step further, replacing all of the macro types with explicitly wide characters: `wchar_t`, `wchar_t*`, `L"..."` etc. – Cody Gray - on strike May 24 '14 at 03:26

first chance exception when i use messagebox

1 Answers1