Strange value when printing out integer [closed]

Question

#include <stdio.h>

int leapyear(int year)
{
    if((year % 4 != 0) && (year % 400 != 0) || (year % 100 == 0))
    {
        printf("Year %d is not leap year.\n", year);
        return 0;
    }
    else
    {
        printf("Year %d is leap year.\n", year);
        return 1;
    }
}

int addDate(int month, int date)
{
     int i, febDate = 0, sum = 0, year;
     if(leapyear(year) == 1)
     {
        febDate += 29;
     }
     else
     {
        febDate += 28;
     }
     for(i = 1; i < month; i++)
     {
         if((i <= 7) && (i != 2) && (i % 2 == 0)) 
         {
             sum += 30;
         }
         else if(i == 2)  
         {
             sum += febDate;
         }
         else if((i >= 8) && (i % 2 != 0)) 
         {
             sum += 30;
         }
         else 
         {
             sum += 31;
         }
      }
    return sum + date;
}

int main(void)
{
    int month, date, year;
    printf("Enter Month: ");
    scanf("%d", &month);
    printf("Enter Date: ");
    scanf("%d", &date);
    printf("Enter Year: ");
    scanf("%d", &year);
    leapyear(year);
    printf("%d days from Jan 1st to %d %d.\n", addDate(month, date), month, date);
    return 0;
}

When I put in 8 22, 2016, I get the following:

Enter Month: 8
Enter Date: 22
Enter Year: 2016
Year 2016 is leap year.
Year -1249813628 is leap year.
235 days from Jan 1st to 8 22.

Everything looks okay except for that "Year -1249813628 is leap year." part.

What could be causing this? I tried having the main function at the very top but didn't fix the problem.

Answer 1

In the addDate function you call leapyear again, but now with the uninitialized local variable year.

Uninitialized local variables will have an indeterminate value (think of it as garbage). In C++ using indeterminate values will lead to undefined behavior.

You should pass year as an argument to the function instead.

int addDate(int year, int month, int date)