Strange value when printing out integer

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.

You tagged your question with the C++ language tag. But there's really nothing specific to C++ in the code you show. It could be compiled with a plain C compiler. Whatever source you use to learn C++ it's not teaching C++. Please invest in [some good C++ books](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list/388282#388282) instead. — Some programmer dude, May 06 '22 at 07:35
`int i, febDate = 0, sum = 0, year;` What is the value of `year` after this line? — Martin York, May 06 '22 at 07:40
I put c++ because I was using Dev C++ instead of visual studios. Mb — ethan, May 12 '22 at 05:59

score 1 · Answer 1 · answered May 06 '22 at 07:32

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)

Strange value when printing out integer

1 Answers1