Leap year program prints wrong output

This is a discussion on Leap year program prints wrong output within the C Programming forums, part of the General Programming Boards category; Hi, This program is supposed to print all the leap year between any two given years. It seems to work ...

  1. #1
    Registered User
    Join Date
    Aug 2003
    Posts
    71

    Leap year program prints wrong output

    Hi,

    This program is supposed to print all the leap year between any two given years. It seems to work when the gap between years is huge, but when I enter 1991 and 2005 for example, it will only tell me that 2000 is a leap year, when years such as 92,96, and 04 are also leap years, right?

    Any ideas where Iv'e gone wrong?

    Code:
    #include <stdio.h>
    #include <process.h>
    #include <values.h>
    
    int main(void)
    {
       char  your_name[12];
       int   year_start;
       int   year_finish;
       int   leap_yr_input = 0;
       int   leap_yr_test = 0;
       int   maxint_value;
       int   i;
       int   yr_test;
       int   nearest_leap_yr;
    
       system("cls");
    
       printf("\nPlease enter your name(e.g. Jan): ");
       scanf("%s", your_name);
    
       maxint_value = MAXINT;
    
       do
       {
          printf("\nEnter year to begin with between 1 and %d: ", maxint_value - 1);
          scanf("%d", &year_start);
    
          printf("\nEnter an ending year between %d and %d(e.g. %d): ",
                 year_start + 1, maxint_value, year_start + 1);
          scanf("%d", &year_finish);
    
          printf("\n");
    
          if(year_start >= year_finish)
          {
             printf("\nInvalid input!");
             printf("\nThe ending year must be bigger than the starting year!");
             printf("\n\nRe-enter years");
          }
       }
       while( year_start >= year_finish );
    
       printf("\nHello %s!", your_name);
       printf("\n");
       printf("\nYour starting year is: %d", year_start);
       printf("\nYour ending year is: %d", year_finish);
       printf("\n\n");
    
       for( i = year_start; i <= year_finish; i++ )
       {
          if( i % 4000 != 0 )
          {
             if( i % 4 == 0 )
             {
                if( i % 400 == 0 )
                {
                   leap_yr_input = 1;
                   printf("\nThe year %d is a leap year", i);
                }
             }
          }
       }
    
       if( leap_yr_input == 1 )
          printf("\n\nThis is the end of LEAP year list");
    
       if( leap_yr_input == 0 )
       {
          printf("\nThere are no leap years in your input range");
    
          for( yr_test = year_finish + 1; yr_test <= maxint_value; yr_test ++)
          {
             if(yr_test % 4000!= 0)
             {
                if(yr_test % 4 == 0)
                {
                   if(yr_test % 400 == 0)
                   {
                      leap_yr_test = 1;
                      nearest_leap_yr = yr_test;
                      break;
                   }
                   else if(yr_test % 100 != 0)
                   {
                      leap_yr_test = 1;
                      nearest_leap_yr = yr_test;
                      break;
                   }
                }
             }
          }
    
          if( leap_yr_test == 0)
          {
             printf("\nThere is NO leap year in the range between ");
             printf("your input and MAXINT");
          }
    
          if(leap_yr_test == 1)
          {
             printf("\n\nThe nearest leap year that is greater than your input ");
             printf("is: %d", nearest_leap_yr);
          }
       }
    
       printf("\n");
       printf("\nThanks for using this program! ");
       printf("Good-bye!");
    
       system("pause");
    }
    Last edited by Guti14; 08-23-2004 at 11:25 PM.

  2. #2
    & the hat of GPL slaying Thantos's Avatar
    Join Date
    Sep 2001
    Posts
    5,681
    first things first
    Code:
    void main()

  3. #3
    C++ Developer XSquared's Avatar
    Join Date
    Jun 2002
    Location
    Ontario, Canada
    Posts
    2,718
    Take out the i % 400 line in your first loop. Otherwise you'll only get years divisible by 400.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  4. #4
    Registered User KonArtis's Avatar
    Join Date
    Mar 2003
    Posts
    34
    Theres a problem with how the leap year is checked.

    This will return 1 if the year is a leap year.
    Code:
    int LeapYear(int iYear)
    {
    	int iReturn=0;
    
    	if ( !(iYear % 4) )
    	{
    		iReturn=1;
    		if ( (iYear % 100) && !(iYear % 400) )
    			iReturn=0;
    	}
    
    	return iReturn;
    }
    Hope this helps
    -Joe

  5. #5
    Gawking at stupidity
    Join Date
    Jul 2004
    Location
    Oregon, USA
    Posts
    3,164
    This will probably execute a little faster:
    Code:
    #define IsLeapYear(y) (!((y)%4) && ((y)%100 || !((y)%400)))
    If you understand what you're doing, you're not learning anything.

  6. #6
    ---
    Join Date
    May 2004
    Posts
    1,379
    at the cost of confusing code
    'macro functions are the tool of the devil!'

  7. #7
    Gawking at stupidity
    Join Date
    Jul 2004
    Location
    Oregon, USA
    Posts
    3,164
    Quote Originally Posted by sand_man
    at the cost of confusing code
    'macro functions are the tool of the devil!'
    Huh? Maybe it's a personal preference issue. Even libc uses macros extensively. The only way it would act any different is if you passed something that had issues with being evaluated more than once to the macro (i.e. IsLeapYear(year++); or IsLeapYear(rand()%4000)
    If you understand what you're doing, you're not learning anything.

  8. #8
    and the hat of wrongness Salem's Avatar
    Join Date
    Aug 2001
    Location
    The edge of the known universe
    Posts
    32,592
    But there's no need for pointless macro-isation of everything simply on the basis of "because I can"

    Just because your expression doesn't contain any if statements doesn't mean it isn't riddled with hidden jump instructions for example.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  9. #9
    Gawking at stupidity
    Join Date
    Jul 2004
    Location
    Oregon, USA
    Posts
    3,164
    I didn't macri-ize it just because I could. I found KonArtis' function unnecessarily difficult to follow so I originally rewrote it as:
    Code:
    int IsLeapYear(int y)
    {
      return (!(y%4) && (y%100 || !(y%400)));
    }
    But since it turned out to be a simple 1-liner I thought it might do well as a macro. It's not like I try to turn every function I see into a macro "just because I can".

    And when I said the macro will run faster I based it on 2 assumptions: 1) no stack overhead from calling the function, 2) eliminating the local variable iReturn in KonArtis' function.

    Still, I'm 99.9% sure the macro will run faster than KonArtis' function on most computers. If you prefer the function then go for it.
    Last edited by itsme86; 08-24-2004 at 12:00 PM.
    If you understand what you're doing, you're not learning anything.

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. why does this program say 1700 is a leap year?
    By newbcore in forum C Programming
    Replies: 7
    Last Post: 12-19-2008, 01:03 AM
  2. Basic C input output program help
    By trevordunstan in forum C Programming
    Replies: 2
    Last Post: 01-27-2008, 05:41 PM
  3. Help with Day Month Year Program..due by 12
    By jgassen15 in forum C Programming
    Replies: 1
    Last Post: 12-06-2007, 10:21 PM
  4. Help! Right Math, Wrong Output
    By verd in forum C Programming
    Replies: 12
    Last Post: 03-15-2005, 06:49 PM
  5. HELP with starting out.
    By sworc66 in forum C Programming
    Replies: 4
    Last Post: 09-05-2002, 10:09 AM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21