| ANSWER TO EXERCISE 72 | |
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The time of day will be returned as a number in the usual Inform time format: as hours times 60 plus minutes (on the 24-hour clock, so that the 'hour' part is between 0 and 23).
Constant TWELVE_HOURS = 720;
[ NumericTime hr mn word x;
if (hr>=24) return -1;
if (mn>=60) return -1;
x=hr*60+mn; if (hr>=13) return x;
x=x%TWELVE_HOURS; if (word=='pm') x=x+TWELVE_HOURS;
if (word~='am' or 'pm' && hr==12) x=x+TWELVE_HOURS;
return x;
];
[ MyTryNumber wordnum i j;
i=wn; wn=wordnum; j=NextWordStopped(); wn=i;
switch(j)
{ 'twenty-five': return 25;
'thirty': return 30;
default: return TryNumber(wordnum);
}
];
[ TimeOfDay i j k flag loop ch hr mn;
i=NextWord();
switch(i)
{ 'midnight': parsed_number=0; return 1;
'midday', 'noon': parsed_number=TWELVE_HOURS; return 1;
}
! Next try the format 12:02
j=WordAddress(wn-1); k=WordLength(wn-1);
flag=0;
for (loop=0:loop<k:loop++)
{ ch=j->loop;
if (ch==':' && flag==0 && loop~=0 && loop~=k-1) flag=1;
else { if (ch<'0') flag=-1; if (ch>'9') flag=-1; }
}
if (k<3) flag=0; if (k>5) flag=0;
if (flag==1)
{ for (loop=0:j->loop~=':':loop++, hr=hr*10)
hr=hr+j->loop-'0';
hr=hr/10;
for (loop++:loop<k:loop++, mn=mn*10)
mn=mn+j->loop-'0';
mn=mn/10;
j=NextWordStopped();
parsed_number=NumericTime(hr, mn, j);
if (parsed_number<0) return -1;
if (j~='pm' or 'am') wn--;
return 1;
}
! Next the format "half past 12"
j=-1; if (i=='half') j=30; if (i=='quarter') j=15;
if (j<0) j=MyTryNumber(wn-1); if (j<0) return -1;
if (j>=60) return -1;
k=NextWordStopped();
if (k==-1)
{ hr=j; if (hr>12) return -1; jump TimeFound; }
if (k=='o^clock' or 'am' or 'pm')
{ hr=j; if (hr>12) return -1; jump TimeFound; }
if (k=='to' or 'past')
{ mn=j; hr=MyTryNumber(wn);
if (hr<=0)
{ switch(NextWordStopped())
{ 'noon', 'midday': hr=12;
'midnight': hr=0;
default: return -1;
}
}
if (hr>=13) return -1;
if (k=='to') { mn=60-mn; hr=hr-1; if (hr==-1) hr=23; }
wn++; k=NextWordStopped();
jump TimeFound;
}
hr=j; mn=MyTryNumber(--wn);
if (mn<0) return -1; if (mn>=60) return -1;
wn++; k=NextWordStopped();
.TimeFound;
parsed_number = NumericTime(hr, mn, k);
if (parsed_number<0) return -1;
if (k~='pm' or 'am' or 'o^clock') wn--;
return 1;
];
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