• atzensepp (55/55) Jan 22 Dear D-gurus,
• Mengu (8/17) Jan 28 If your date conforms to an ISO or extended ISO format, you can
• Steven Schveighoffer (6/14) Jan 31 That's how I would do it also.

atzensepp <webwicht web.de> writes:

Dear D-gurus,

being new to D I am trying my first steps and the language is 
quite intuitive and appealing.
When reading a file and creating a hash for the reocrds I want to 
get only the most recent ones. For this I need to convert 
Date/Time-Strings to comparable DateTime-Objects.
The code below works but looks a bit clumsy. Is there a more 
efficient (shorter) way to accomplish this?

Thanks in advance


```d
// Read lines using foreach.
void main( string args[])
{
     auto file = File(args[1]);// Open for reading
     auto range = file.byLineCopy();
     auto iline=0;
     int  idxARE=2,idxDC=3,idxTD=0;

     string [] records[string];

     DateTime getDateTime( string [] row)
     {
         int d,m,y,ho,mi,se;
         row[0].formattedRead!"%d.%d.%d"(d, m, y);
         row[1].formattedRead!"%d:%d:%d"(ho, mi, se);
         return DateTime(y,m,d,ho,mi,se);
     }

     foreach (line; range)
     {
         if (!line.empty)
         {
             string [] row = line.split(";");

             string key = [row[2], row[3]].join("_"); // unique key
             if(iline>0) // skip header line
             {
                if(key in records)
                {
                   // do we have a newer one?
                   if( getDateTime(row) > 
getDateTime(records[key]))
                   {
                      records[key]=row;
                      writeln("UPDATE:",key);
                   }
                } else
                {
                   // first one:
                   records[key]=row;
                }
               }
             iline++;
         }
     }

     writeln( records.length);
     writeln("Lines: ",i);
}

```

Mengu <mengukagan gmail.com> writes:

On Monday, 22 January 2024 at 10:56:04 UTC, atzensepp wrote:
 Dear D-gurus,

 being new to D I am trying my first steps and the language is 
 quite intuitive and appealing.
 When reading a file and creating a hash for the reocrds I want 
 to get only the most recent ones. For this I need to convert 
 Date/Time-Strings to comparable DateTime-Objects.
 The code below works but looks a bit clumsy. Is there a more 
 efficient (shorter) way to accomplish this?

 [...]

If your date conforms to an ISO or extended ISO format, you can 
use DateTime.fromISOString [0] or DateTime.fromISOExtString [1] 
functions.

[0] 
https://dlang.org/phobos/std_datetime_date.html#.Date.fromISOString
[1] 
https://dlang.org/phobos/std_datetime_date.html#.Date.fromISOExtString

Steven Schveighoffer <schveiguy gmail.com> writes:

On Monday, 22 January 2024 at 10:56:04 UTC, atzensepp wrote:
 Dear D-gurus,

 being new to D I am trying my first steps and the language is 
 quite intuitive and appealing.
 When reading a file and creating a hash for the reocrds I want 
 to get only the most recent ones. For this I need to convert 
 Date/Time-Strings to comparable DateTime-Objects.
 The code below works but looks a bit clumsy. Is there a more 
 efficient (shorter) way to accomplish this?

That's how I would do it also.

I would note there also is a library I've used which works pretty 
well:

https://code.dlang.org/packages/dateparser

-Steve