• Greatsam4sure (10/10) Jul 24 2019 int main(){
• drug (4/16) Jul 24 2019 does it help?
• a11e99z (6/16) Jul 24 2019 readf!" %s\n"( num );
• a11e99z (2/21) Jul 24 2019 oops! i misunderstood
• Greatsam4sure (4/27) Jul 24 2019 writeln(num)
• a11e99z (4/10) Jul 24 2019 see another answers at thread
• Simen =?UTF-8?B?S2rDpnLDpXM=?= (23/49) Jul 24 2019 So, there are several possible issues here. First, floating-point
• a11e99z (13/23) Jul 24 2019 as drug said: writefln with formatting

Greatsam4sure <greatsam4sure gmail.com> writes:

int main(){
  double mum = 0;
  Write("enter a number: ")
  readf(" %s\n",&num);
  Writeln(num);

}

How do I return the complete number the user enter since I don't 
since the user can enter numbers of various length with dmd 
approximating it.

I will appreciate any help

drug <drug2004 bk.ru> writes:

24.07.2019 18:45, Greatsam4sure пишет:
 int main(){
   double mum = 0;
   Write("enter a number: ")
   readf(" %s\n",&num);
   Writeln(num);
 
 }
 
 How do I return the complete number the user enter since I don't since 
 the user can enter numbers of various length with dmd approximating it.
 
 I will appreciate any help

does it help?

writefln("%.8f", num); // for float

writefln("%.16f", num); // for double

a11e99z <black80 bk.ru> writes:

On Wednesday, 24 July 2019 at 15:45:08 UTC, Greatsam4sure wrote:
 int main(){
  double mum = 0;
  Write("enter a number: ")
  readf(" %s\n",&num);
  Writeln(num);

 }

 How do I return the complete number the user enter since I 
 don't since the user can enter numbers of various length with 
 dmd approximating it.

 I will appreciate any help

   readf!" %s\n"( num );
or
   num.readf!" %s\n";
or
   num = readln.strip.to!double;

a11e99z <black80 bk.ru> writes:

On Wednesday, 24 July 2019 at 15:56:13 UTC, a11e99z wrote:
 On Wednesday, 24 July 2019 at 15:45:08 UTC, Greatsam4sure wrote:
 int main(){
  double mum = 0;
  Write("enter a number: ")
  readf(" %s\n",&num);
  Writeln(num);

 }

 How do I return the complete number the user enter since I 
 don't since the user can enter numbers of various length with 
 dmd approximating it.

 I will appreciate any help

   readf!" %s\n"( num );
 or
   num.readf!" %s\n";
 or
   num = readln.strip.to!double;

oops! i misunderstood

Greatsam4sure <greatsam4sure gmail.com> writes:

On Wednesday, 24 July 2019 at 15:57:06 UTC, a11e99z wrote:
 On Wednesday, 24 July 2019 at 15:56:13 UTC, a11e99z wrote:
 On Wednesday, 24 July 2019 at 15:45:08 UTC, Greatsam4sure 
 wrote:
 int main(){
  double mum = 0;
  Write("enter a number: ")
  readf(" %s\n",&num);
  Writeln(num);

 }

 How do I return the complete number the user enter since I 
 don't since the user can enter numbers of various length with 
 dmd approximating it.

 I will appreciate any help

   readf!" %s\n"( num );
 or
   num.readf!" %s\n";
 or
   num = readln.strip.to!double;


       writeln(num)

The result is always to six significant figure. I want the whole 
number to be diaplay
 oops! i misunderstood

a11e99z <black80 bk.ru> writes:

On Wednesday, 24 July 2019 at 16:16:15 UTC, Greatsam4sure wrote:
 On Wednesday, 24 July 2019 at 15:57:06 UTC, a11e99z wrote:
 On Wednesday, 24 July 2019 at 15:56:13 UTC, a11e99z wrote:
 On Wednesday, 24 July 2019 at 15:45:08 UTC, Greatsam4sure


 The result is always to six significant figure. I want the 
 whole number to be display


see another answers at thread
https://forum.dlang.org/post/qh9v10$19v1$1 digitalmars.com
https://forum.dlang.org/post/afzqnnorzwosimfqnbcb forum.dlang.org

Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:

On Wednesday, 24 July 2019 at 16:16:15 UTC, Greatsam4sure wrote:
 On Wednesday, 24 July 2019 at 15:57:06 UTC, a11e99z wrote:
 On Wednesday, 24 July 2019 at 15:56:13 UTC, a11e99z wrote:
 On Wednesday, 24 July 2019 at 15:45:08 UTC, Greatsam4sure 
 wrote:
 int main(){
  double mum = 0;
  Write("enter a number: ")
  readf(" %s\n",&num);
  Writeln(num);

 }

 How do I return the complete number the user enter since I 
 don't since the user can enter numbers of various length 
 with dmd approximating it.

 I will appreciate any help

   readf!" %s\n"( num );
 or
   num.readf!" %s\n";
 or
   num = readln.strip.to!double;


       writeln(num)

 The result is always to six significant figure. I want the 
 whole number to be diaplay

So, there are several possible issues here. First, floating-point 
numbers have limited precision - a double can not correctly 
represent all integers above 2^52, for instance. That's 4.5 
quadrillion though, so rarely an issue. In your case, as others 
have commented, writefln with a correctly chosen format string[1] 
will do the trick.

However, what is the correctly chosen format string? This is a 
very hard question to answer, as it depends on what number was 
typed, and what you mean by 'the complete number the user enter'. 
While drug's suggestion of "%.16f" will return an accurate 
representation of the floating-point number, it will include a 
lot of trailing zeroes that were presumably not present in the 
input string. It will also expose floating-point's limitations 
when presented with huge numbers, like 1e23 will print 
99999999999999991603000.0000000000000000. The best option might 
be "%.16g", which will choose the shortest of the scientific 
notation and the regular notation, as well as strip trailing 
zeroes. Depending on the criteria though, this might still not be 
the optimal solution.

--
   Simen


1: https://dlang.org/phobos/std_format.html#format-string

a11e99z <black80 bk.ru> writes:

On Wednesday, 24 July 2019 at 15:45:08 UTC, Greatsam4sure wrote:
 int main(){
  double mum = 0;
  Write("enter a number: ")
  readf(" %s\n",&num);
  Writeln(num);

 }

 How do I return the complete number the user enter since I 
 don't since the user can enter numbers of various length with 
 dmd approximating it.

 I will appreciate any help

as drug said: writefln with formatting
in case no need prints just string representation use
   s/format https://dlang.org/phobos/std_format.html#format
auto str = num.format!"%.16s"; // using UFCS
or
auto str = "%.16s".format( num); // UFCS too for 2nd version of 
format
or
string str = format( "%.16s", num);

simple help can be asked on IRC channel too 
irc://irc.freenode.net/d
(HexChat, mIRC clients and others)