Should I use wsprintf() to print a double as a wide string?

Question

I am unable to print double value using wsprintf(). I tried sprintf() and it worked fine.

Syntax used for wsprintf() and sprintf() is as follows:

wsprintf(str,TEXT("Square is %lf "),iSquare); // Does not show value

sprintf(str," square is %lf",iSquare);  // works okay

Am I making any mistakes while using wsprintf() ?

Answer 1

wsprintf doesn't support floating point. The mistake is using it at all.

If you want something like sprintf, but for wide characters/strings, you want swprintf instead.

Actually, since you're using the TEXT macro, you probably want _stprintf instead though: it'll shift from a narrow to wide implementation in sync with the same preprocessor macros as TEXT uses to decide whether the string will be narrow or wide. This whole approach, however, is largely a relic from the days when Microsoft still sold and supported versions of Windows based on both the 32-bit NT kernel, and on the 16-bit kernel. The 16-bit versions had only extremely minimal wide-character support, so Microsoft worked hard at allowing a single source code base to be compiled to use either narrow characters (targeting 16-bit kernels) or wide characters (to target the 32-bit kernels). The 16-bit kernels have been gone for long enough that almost nobody really has much reason to support them any more.

For what it's worth: wsprintf is almost entirely a historic relic. The w apparently stands for Windows. It was included as part of Windows way back when (back to the 16-bit days). It was written without support for floating point because at that time, Windows didn't use any floating point internally--this is part of why it has routines like MulDiv built-in, even though doing (roughly) the same with floating point is quite trivial.

Answer 2

The function wsprintf() does not support floating point parameters, try using swprintf() instead if you're working with floating point values.

More information about swprint can be found here

Answer 3

wsprintf does not support floating point. See its documentation - lf is not listed as a valid format code.

The swprintf function part of the Visual Studio standard library is what you want. It supports all of the format codes that sprintf does.