Default case doesn't get executed c++ - c++

Question

I have this function that checks whether a date is within range.
bool check_date(const int &in_day, const int &in_month, const int &in_year)
{
if (in_year < 1582)
return false;
else if (in_year == 1582 && in_month < october)
return false;
else if (in_month < 1 || in_month > 12)
return false;
switch (in_month)
{
case january: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case february: // 28 days, 29 if leap.
if (is_leap(in_year))
{
if (in_day > 29 || in_day < 1)
return false;
}
else
{
if (in_day > 28 || in_day < 1)
return false;
}
case march: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case april: // 30 days
if (in_day < 1 || in_day > 30)
return false;
break;
case may: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case june: // 30 days
if (in_day < 1 || in_day > 30)
return false;
break;
case july: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case august: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case september: // 30 days
if (in_day < 1 || in_day > 30)
return false;
break;
case october: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case november: // 30 days
if (in_day < 1 || in_day > 30)
return false;
break;
case december: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
default:
std::cout <<"CORRECT DATE";
}
return true;
}
While the code works as in it returns true and false where it should, the default: case never gets selected, even when the date is correct, for example where in_day = 17, in_month = 9, in_year = 1999. At first I had return true; inside the default case, but it would never return true, and after running the debugger I found that the default case never ran, so I moved return out of the switch statement (it works there). Am I doing something wrong, why doesn't the default case execute?

Answer 1

default would be executed if you pass anything except january-dec
Since you test the range before the switch - you never enter the default case.
What you need to do - is take your
std::cout <<"CORRECT DATE";
out of the switch and put it before return true; - you will get there from any case when your test is passed and you did not return false - instead - going to break branch.

Answer 2

It is unreachable code.
The default inside switch (in_month) is equal to
if (in_month < 1 || in_month > 12) return false;
So if you want to use default inside switch (in_month) you don't need if (in_month < 1 || in_month > 12) see:
switch (in_month) {
default: // if (in_month < 1 || in_month > 12)
std::cout << "BAD month: ";
return false;
see this optimized and cleaned code:
#include <iostream>
using namespace std;
enum {
january = 1,
february,
march,
april,
may,
june,
july,
august,
september,
october,
november,
december
};
bool is_leap(const int year) {
if (year % 400 == 0)
return true;
if (year % 100 == 0)
return false;
if (year % 4 == 0)
return true;
return false;
}
bool check_date(const int in_day, const int in_month, const int in_year) {
if (in_year < 1582)
return false;
if (in_year == 1582 && in_month < october)
return false;
switch (in_month) {
default: // if (in_month < 1 || in_month > 12)
std::cout << "BAD DATE: ";
return false;
case january: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case february: // 28 days, 29 if leap.
if (is_leap(in_year)) {
if (in_day > 29 || in_day < 1)
return false;
} else {
if (in_day > 28 || in_day < 1)
return false;
}
break;
case march: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case april: // 30 days
if (in_day < 1 || in_day > 30)
return false;
break;
case may: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case june: // 30 days
if (in_day < 1 || in_day > 30)
return false;
break;
case july: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case august: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case september: // 30 days
if (in_day < 1 || in_day > 30)
return false;
break;
case october: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
case november: // 30 days
if (in_day < 1 || in_day > 30)
return false;
break;
case december: // 31 days
if (in_day < 1 || in_day > 31)
return false;
break;
}
std::cout << " CORRECT DATE: ";
return true;
}
int main() {
cout << check_date(0, 0, 2017) << endl; // 0
cout << check_date(29, 2, 2000) << endl; // 1
cout << check_date(29, 2, 2017) << endl; // 0
cout << check_date(1, 1, 2017) << endl;
cout << check_date(1, 1, 2017) << endl;
cout << check_date(1, 1, 2017) << endl;
}
output:
BAD month: 0
CORRECT DATE: 1
0
CORRECT DATE: 1
CORRECT DATE: 1
CORRECT DATE: 1