Precision, new prices

[Saaa]

I thought my previous precision question was so retarded it didn't need any 
explanation; anybody here could easily tell me my fault in reasoning.

Here is my question again but this time with examples.

Is there some formatting which lets me print out a floating point in full 
precision?

Observation: 6 digits is not full precision:

float f=3.4028234; // 0x7f7f ffff
writefln("%.8g",f); // prints 3.4028234
writefln(f.dig); // prints 6
writefln(3.4028234f.dig); // prints 6

Shouldn't f.dig print out 8?
.dig =  number of decimal digits of precision

I still think I don't get something, somewhere.