Hello Martin, > recently i have actived the -Wconverion flag of g++-4.4.1 on my Ubuntu > linux system. It brought up a warning > (http://trac.wxwidgets.org/ticket/11252). Now my question: g++ warns > about, that it may change the value. How to make do it correctly? Is > there a function to check a float number fits into an integer? Avoiding the warning is quite easy: do an explicit cast: If you write: float f = 2.1f; int x = (int)f; you won't obtain a warning. Determining whether it is an integer is a bit more complex (at least I don't remember a direct function right now). However: if( ceil(f) == floor(f) ) will be a good start. If you want to be more precise, you should check in addition, that f is not NAN: if( isnormal(f) && ceil(f) == floor(f) ) should be more general. However, isnormal is only defined in C99... Last remark: ceil and floor return floats - so in addition you can have an overflow. I think, you are on the save side with a check like: if ( isnormal(f) && ceil(f) == floor(f) && floor(f) < INT_MAX && floor(f) > INT_MIN ) INT_MIN and INT_MAX are defined in limits.h. Axel
