floating point value rounded to 6digits

[Ivan Kazmenko]

On Tuesday, 19 September 2017 at 20:47:02 UTC, greatsam4sure 
wrote:
> double  value = 20.89766554373733;
> writeln(value);
> //Output =20.8977
>
> How do I output the whole value without using writfln,write or 
> format. How do I change this default

The default when printing floating-point numbers is to show six 
most significant digits.
You can specify the formatting manually with writefln, for 
example,

     writefln ("%.10f", value);

will print the value with 10 digits after the decimal point.
The writef/writefln function behaves much like printf in C.

See here for a reference on format strings:
https://dlang.org/library/std/format/formatted_write.html#format-string

Ivan Kazmenko.