Check floats for .nan

[Acarion]

I have this code:

float number=getFloat();
assert(number!=float.nan); //this passes
assert(to!(char[])(number)!="nan"); //this fails
writefln(string.toString(number)); //this outputs: "nan"
writefln( to!(char[])(to!(long)(number)) ); //this generates an error

What did I do wrong?