/**********************  04-2-S.TXT  ********************
 ***********  Prof. Dr. B. Bartning *********************/

- Remarks about solutions -
ATTENTION, please, here are only program fragments,
this file cannot be compiled as a whole!!
- WITHOUT guarantee! -

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01 // multiple selection

02 // Program outputs the number of days of the month monthNumber
03 //   in a non-leap year

04 #include <iostream.h>

05 int main()
06 {
07   int monthNumber, numDays;

08   cin >> monthNumber;

09   switch (monthNumber) {

10     case  1:
11     case  3:
12     case  5:
13     case  7:
14     case  8:
15     case 10:
16     case 12: numDays=31; break;

17     case  4:
18     case  6:
19     case  9:
20     case 11: numDays=30; break;

21     case  2: numDays=28; break;
22   }

23   cout << numDays << endl;

24   return 0;
25 }


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(a)
Before 09:
  if (monthNumber < 1 || monthNumber > 12)
     cout << "Please, input only month numbers between 1 and 12!" << endl;
  else {

After 23:
  }

ATTENTION: in the ELSE branch ("else"), there must appear two statements
(switch AND output "cout << numDays ..", because otherwise when wrong
monthNumber, a non assigned value for numDays would be written. Therefore
make a block with the brace pair { ... } !


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(b)
07new   int monthNumber, yearNumber, numDays;

08new   cin >> monthNumber >> yearNumber;

21new   if (yearNumber%4==0) numDays=29; // leap year
        else numDays=28;

or (AFTER explaination of (5.12)):
         numDays = (yearNumber%4==0) ? 29 : 28;

(c)
like (b), however:
21newnew  if (yearNumber%4==0 && (yearNumber%100!=0 || yearNumber%400==0))
             numDays=29;
          else numDays=28;
Parentheses around the Or part (||) are necessary because Or has a
lower precedence.

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(d) Do it yourself!

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(e) - here still WITHOUT a reading loop; loop see (5.26d) -

Before 09:
  if (!cin)
     cout << "Please, input only digits!" << endl;
  else if (monthNumber < 1 || monthNumber > 12)
     cout << "Please, input only month numbers between 1 and 12!" << endl;
  else {

After 23:
  }

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