my problem...

need help with my program, it's a Julian Date conversion. The part that i'm having difficulty with is when you enter a julian date, there are 6 numbers after the decimal. How do i get the 6 numbers after the decimal so that i can calculate the hours, minutes and seconds?? here's my code:

Code:

#include <stdio.h> int main() { double jdn; long lc, nc, ic, jc; int day, month, year, hours, minutes, seconds, a, b, meridian ; /*print title*/ printf(" * * Julian Date Conversion * *\n") ; /*ask user for a Julian date */ printf ("Please enter a Julian Date:\n") ; scanf("%lf", &jdn) ; if (jdn <= 2299160) printf ("Error: You have entered an invalid number.") ; /* Perform calculations */ lc = jdn + 68569; nc = 4 * lc / 146097; lc = lc - (146097 * nc + 3) / 4; ic = 4000 * (lc + 1) / 1461001; lc = lc - 1461 * ic / 4 + 31; jc = 80 * lc / 2447; day = lc - 2447 * jc / 80; lc = jc / 11; month = jc + 2 - 12 * lc; year = 100 * (nc - 49) + ic + lc; hours= jdn % * 24 ; a= hours % 60 ; minutes= a * 60 ; b= minutes % 60 ; seconds= b * 60 ; if (meridian >= 12) printf ("p.m.") ; else printf ("a.m.") ; /* print date*/ printf("%d %d %d %d %d %d\n", month, day, year, hours, minutes, seconds, meridian); return 0; }

my problem more specifically, is in the calculations portion where hours begins. to help understand what i mean:
Calculation of time portion:
(0.1 days equals 0.1 * 24 hours = 2 hours (remainder 0.4 hours),
0.4 * 60 minutes = 24 minutes (remainder 0.0 seconds)
0.0 * 60 seconds = 0 seconds

I dont know how to get only the numbers after the decimal, or if there is another way i dont see it yet, so that i can calculate the hours, minutes, and seconds!! please help.

Quote:

Originally Posted by lyojarhhs

there are 6 numbers after the decimal. How do i get the 6 numbers after the decimal so that i can calculate the hours, minutes and seconds?

If you truncate the double jdn by storing it into a long integer and then subtract that integer from jdn you'll be left with the decimal part. You could then multiply by 1,000,000 to move it up past the decimal if it's easier.

I'm not sure i did what you asked, but i tried:

jdn = lc; /*truncate*/
jdn - lc ;
hours= jdn * 24 ;
a= jdn % 60 ;
minutes= a * 60 ;
b= minutes % 60 ;
seconds= b * 60 ;

when i try to compile i get an error message saying "Operations between types 'double' and 'int' is not allowed"..
obviously im doing something wrong.

The modulus operator is an integer operation and jdn is a double. That's a problem.

You should use type castin. Like [edited for C]

Code:

jdn = (double)lc; a= (long)jdn % 60 ;

But what is wrong in your code is

Code:

jdn = lc; /*truncate*/ jdn - lc ; /*It just does nothing*/

[EDIT]
No sorry. I didn't noticed there is no assignment.

Quote:

Originally Posted by lyojarhhs

I'm not sure i did what you asked, but i tried:

jdn = lc; /*truncate*/
jdn - lc ;
hours= jdn * 24 ;
a= jdn % 60 ;
minutes= a * 60 ;
b= minutes % 60 ;
seconds= b * 60 ;

when i try to compile i get an error message saying "Operations between types 'double' and 'int' is not allowed"..
obviously im doing something wrong.

No, I was thinking of something like:

Code:

double tm; /* <-------- for storing fractional part */ lc = jdn; /* <------ this gets the integer part; the number of days */ tm = jdn - lc; /* <------ this gets the fractional part of the day */

Your example seems to be obliterating the julian date entered by the user
with an uninitialized integer.

Quote:

Originally Posted by risby

No, I was thinking of something like:

Code:

double tm; /* <-------- for storing fractional part */ lc = jdn; /* <------ this gets the integer part; the number of days */ tm = jdn - lc; /* <------ this gets the fractional part of the day */

Your example seems to be obliterating the julian date entered by the user
with an uninitialized integer.

when i do

lc = jdn;

i still get the message "Operation between types 'double' and 'int' not allowed.

Unless you're on some strange compiler that line won't give you an error... I feel like you probably completely ignored the two posts before it that told you that you can't use a double with the modulus operator. Convert it to an integral type first. I'd almost garuntee that's what's giving you the error.