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Question

why does the variable "calcDayInt" print out to be blank when the difference between desDateYear & todayDateYear is anything more than 5?(c++)

As long as the variables have a difference of 5 or less the code works alright and gives me the correct answer, but as soon as I increase the difference in the condition in the first for loop and make it >5 the variable gives me an empty output.

I tried changing everything and ran through the code manually on a piece of paper, but i cant seem to make it work.

#include <cstdlib>
#include <iostream>
#include <string>
using namespace std;

int main(int argc, char *argv[])
{
  int i;
  int desDateYear = 21;
  int todayDateYear = 15;
  int calcDayInt = 4;
  int calcDateYear = todayDateYear;  

  if(desDateYear>todayDateYear)
    {
      for (i = 0; i < ((desDateYear-todayDateYear)+1); i++)
      {
          if ((calcDateYear)%4==0)
          {
            for (i=0; i<2; i++)
            {
              calcDayInt++;
              if(calcDayInt==8)
              {
                calcDayInt=1;
              }
            }
          }
          if ((calcDateYear)%4!=0)
          {
              calcDayInt++;
              if(calcDayInt==8)
              {
                calcDayInt=1;
              }
          }
          calcDateYear++;
      }
    }
    cout<<calcDayInt;
    system("PAUSE");
    return EXIT_SUCCESS;
}

Answer 1

You are stuck in an infinite loop.

The inner for loop reuses the counter i from the outer loop and overwrites its value. Thus the termination condition for the outer loop is never met and the loop never finishes.

You can use a different variable for the inner loop by changing the loop header to something like

for (int i=0; i<2; i++)

Bonus points for you if you can figure out why it still works for some values and what the exact boundaries are at which it starts to get stuck.