Date manipulation: Difference between revisions

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 ==={{libheader|Gadget}}===
+<p>Version 1: Rosetta Code solution</p>
 <syntaxhighlight lang="c">
 #include <gadget/gadget.h>
@@ Line 519: / Line 520: @@
 Use:
    addhour <nHours>
+</pre>
+<p>Version 2: full solution</p>
+<syntaxhighlight lang="c">
+#include <gadget/gadget.h>
+LIB_GADGET_START
+void write_human_date( const char* date, const char * time )
+{
+    Print "%s %d %d %d:%d%s EST\n", Get_monthname( Get_month( date )-1 ),\
+                                    Get_day( date ), Get_year( date ), \
+                                    Get_hour(time),Get_minute(time), \
+                                    Get_hour(time)>=12 ? "pm" : "am" ;
+}
+Main
+   Assert( Arg_count==2, fail_input );
+   Get_arg_str( cTime, 1 );
+   int addhour;
+   if ( Occurs(":", cTime) ){  // input: hh:mm:ss"
+       int sign = 1;
+       if ( cTime[0] == '-' ) {
+           sign=-1;
+           Fn_let( cTime, Substr( cTime,Str_at("-",cTime)+1,strlen(cTime) ) );
+       }
+       Assert ( Is_time_valid( cTime ), fail_time );
+       addhour = Time2sec( cTime ) * sign;
+   }else if( Occurs(",", cTime) ){  // horas>24 , minutos [0->59]
+       long min=0;
+       String cmin;
+       Stack{
+           addhour = Str2int( Get_token(cTime,1) );
+           min = Time2sec( Multi_copy( cmin, "00:", Get_token(cTime,2),NULL) );
+       }Stack_off;
+       Free secure cmin;
+       if( addhour<0 ) {
+           addhour = addhour*60*60 - min;
+       }else{
+           addhour = addhour*60*60 + min;
+       }
+   }else{
+       addhour = Time2sec( cTime );  // asume hora simple
+   }
+   Free secure cTime;
+   Set_date_lang( EN );  // fix english language
+   char * date = Get_date();
+   char * time = Get_time();
+   int SGN = Sign(addhour);
+   write_human_date(date, time);
+   int adddays=0;
+   if( Is_non_neg(addhour) ){
+      adddays = ( Time2sec(time) + addhour ) / 86400;
+      Get_fn_let( time, Sec2time( (Time2sec(time) + addhour )) );
+      Get_fn_let( date, Date_add( date, adddays ) );
+   }else{
+      int ts = Time2sec(time), nt = addhour;
+      int subdays = ( Time2sec(time) + SGN*addhour ) / 86400;
+      if( SGN*nt > ts ){
+          Fn_let( time, Sec2time( 86400*subdays - SGN * (Time2sec(time) + addhour )) );
+      }else{
+          if( SGN*addhour/60/60 <= Get_hour(time) && Is_non_zero(subdays) )
+              subdays--;
+          Fn_let( time, Sec2time( (Time2sec(time) + addhour )) );
+      }
+      Get_fn_let( date, Date_add( date, SGN*subdays ) );
+   }
+   write_human_date(date, time);
+   Free secure date, time;
+  Exception( fail_input ){
+     Msg_yellow("Use:\n   addhour <[-]nHours|[-]hh:mm[:ss]|[-]hh,mm>\n"
+             "e.g.\n addhour 12 (add 12 hours)\n addhour 12:15 (add 12 hours + 15 mins)\n"
+             " addhour -04:45 (subtract 4 hours + 45 mins)\n"
+             " addhour 72 (add 72 hours)\n addhour -48,3 (subtract 48 hours + 3 mins)\n"
+             " addhour 0,-15 (subtract 15 mins = -00:15)");
+  }
+  Exception( fail_time ){
+     Msg_yellowf("Bad format time: %s (valid time: hh:mm[:ss])\n",cTime );
+     Free secure cTime;
+  }
+End
+</syntaxhighlight>
+{{out}}
+<pre>
+$ ./tests/addhour 12
+january 12 2023 15:21pm EST
+january 13 2023 3:21am EST
+$ ./tests/addhour 12:15
+january 12 2023 15:22pm EST
+january 13 2023 3:37am EST
+$ ./tests/addhour -04:45
+january 12 2023 15:22pm EST
+january 12 2023 10:37am EST
+$ ./tests/addhour 72
+january 12 2023 15:22pm EST
+january 15 2023 15:22pm EST
+$ ./tests/addhour -48,3
+january 12 2023 15:22pm EST
+january 10 2023 15:19pm EST
+$ ./tests/addhour 0,-15
+january 12 2023 15:22pm EST
+january 12 2023 15:7pm EST
+$ ./tests/addhour -15,27
+january 12 2023 15:27pm EST
+january 12 2023 0:0am EST
+$ ./tests/addhour -15,28
+january 12 2023 15:27pm EST
+january 11 2023 23:59pm EST
 </pre>