C++ Help trying to solve the puzzles on the spotify

Question

Hi I am trying to solve the puzzles on the spotify website - http://www.spotify.com/uk/jobs/tech/best-before/

I'm writing it in C++ and im getting some very annoying results. I have an int called pause which is usless and does nothing, but when I delete it my program seems to return the wrong result.

    #include <iostream> 
    #include <string>
    #include <sstream>

    using namespace std;
    int Year;
    int Month;
    int Day;

    int pause;  // <--- My useless INT which when Deleted my code returns wrong output

    stringstream ss;
    string input;
    string in;
    bool loop=true;
    int date[3];
    bool DateFound=false;

            void Check_date();
            void Check_date()
        {

if(DateFound==false)
{
//Check if valid Year
if (date[1]<2999 && date[1]>0 && date[2]>0 && date[3]>0) 
{   //check months & days are valid
    if(date[2]==1 || date[2]==3 || date[2]==5 || date[2]==7 || date[2]==8 || date[2]==10 || date[2]==12){if(date[3]<=31){DateFound=true;}}
    if(date[2]==4 || date[2]==6 || date[2]==9 || date[2]==11){if(date[3]<=30){DateFound=true;}}
    //Check For Leap Year
    if (date[2]==2)
    {   if(date[3]<28)DateFound=true;
        if(date[1]%4==0 && date[3]<=29)DateFound=true;
        if(date[1]%100==0 && date[1]%400!=0 && date[3]>28)DateFound=false;
    }

if(DateFound==true){Year=date[1]; Month=date[2]; Day=date[3];}
}
}

      }

        void SwitchDate(){int temp; temp=date[2]; date[2]=date[3]; date[3]=temp; 

    Check_date();};
    void ShiftDate(int places)
    {   if(places==1)
        {
        int temp; temp=date[3]; date[3]=date[2]; date[2]=temp; temp=date[1]; date[1]=date[2]; date[2]=temp;  Check_date();
        }
        if(places==2)
        {
        int temp; temp=date[1]; date[1]=date[2]; date[2]=temp; temp=date[2]; date[2]=date[3]; date[3]=temp; Check_date();
    }
};

int main ()
{   

while(loop==true)
{
cin >> input;
for (int x=0, y=1; y<4; y++, x++)
    {
        while (input[x] !='/' && x !=input.length()) ss<<input[x++];
        ss>> date[y];
        ss.clear();
    }

//order small medium large

for (int x=3, temp; x!=0; x--)
{
    if (date[x] < date[x-1]) 
        {   temp=date[x-1];
            date[x-1]=date[x];
            date[x]=temp;
        }
    if (x==1 && (date[2] > date[3] )) 
            {
                temp=date[3];
                date[3]=date[2];
                date[2]=temp;
            }

}

Check_date();//return true
SwitchDate();
ShiftDate(1);
SwitchDate();
ShiftDate(2);
SwitchDate();

//PRINT

cout <<Year; cout<< endl;
cout <<Month; cout<< endl;
cout <<Day; cout<< endl;

//          13/12/5

cout <<"Again? 'Y' or 'N' \n";
cin >>in;
if(in=="y" || in=="Y"){loop=true;}
if(in=="n" || in=="N"){loop=false;}
}

return 0;
}

Answer 1

int date[3];

You have declared date as an arary of three ints. The three ints are called: date[0], date[1], and date[2].

Yet, in this line

if (date[1]<2999 && date[1]>0 && date[2]>0 && date[3]>0) 

you refer to something called date[3], which doesn't exist.

In C and C++, arrays are zero-based. That is, the first element is indexed by 0. If the array is of size N, then the final element is indexed by N-1.