# date_conv.awk - supply MM/DD/YY/number of days to add or substract

BEGIN{ FS="/" 
split( "Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec", month," "); 
split( "31 28 31 30 31 30 31 31 30 31 30 31", days, " "); 
} 
{ 
year = $3 
leapyear = year % 4; 
if( leapyear == 0 ) 
days[2] = 29 
else 
days[2] = 28; 
doy = 0; 
for ( i = 1; i< $1; i++ ) 
doy = doy + days[i] 
doy = doy + $2; 
if ( doy <= 60 ) 
{ 
doy = doy + 365; 
year = year - 1; 
leapyear = year %4; 
if( leapyear == 0 ) 
{ 
days[2] = 29; 
doy = doy + 1; 
} 
} 
doy = doy + $4; 
for ( i = 1; i <= 12; i++ ) 
{ 
doy = doy - days[i]; 
if ( doy <= 0 ) 
{ 
doy = doy + days[i]; 
break; 
} 
} 
printf( "%d/%d/%d", i, doy, year ) 
}