How to print a float number to visual c++ messagebox?

Question

I have, a float number. I would like to print it inside a messagebox. How to do it?

MessageBox(hWnd, "Result = <float>", L"Error", MB_OK);

update:

I do this and it prints out chinese characters inside the messagebox.

 float fp = 2.3333f;
 sprintf(buffer,"%f",fp);
 MessageBox(hWnd, LPCWSTR(buffer), L"Error", MB_OK);

Answer 1

You have to printf the message to a buffer with the %f format code and then use that in your MessageBox()

Answer 2

As you are using the wchar_t versions of the Win32-functions you should use swprintf instead of sprintf:

float fp = 2.3333f;
const size_t len = 256;
wchar_t buffer[len] = {};
swprintf(buffer, L"%f", fp);
MessageBox(hWnd, buffer, L"Error", MB_OK);

To avoid potential buffer overruns you could also use _snwprintf:

float fp = 2.3333f;
const size_t len = 256;
wchar_t buffer[len] = {};
_snwprintf(buffer, len - 1, L"%f", fp);
MessageBox(hWnd, buffer, L"Error", MB_OK);

Or better yet, use std::wostringstream declared in <sstream>:

float fp = 2.3333f;
std::wostringstream ss;
ss << fp;
MessageBox(hWnd, ss.str().c_str(), L"Error", MB_OK);

Answer 3

You're using the Unicode version of MessageBox, which is why you have to specify the "Error" string with the L prefix -- this tells it that it should use wide (16-bit) chars. As dalle said, this means you must specify the buffer as wchar_t, and use the corresponding wchar_t version of printf.

You'll be seeing Chinese characters because it's interpreting your string of bytes as a string of wchar_t. You are explicitly casting buffer to be a wchar_t string, after all.