Age in Days... But now freehand!?

[Simon Mansfield]

The code has the same end result as the last one.. It must tell the user how
many days it has been since their birthday. Now it does give a result but
its normally off by a bit.. I have figured out which bit of the code is
causing this error, but, can't figure out exactly what is wrong with it! :(

The bit of code that is incorrect I have highlighted below.

#include <stdio.h>

static int YearDb [2][13] = { //A database of the number of days in each
month in a normal and a leap year.
{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
{0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
};

int leapyr(int year) { //Works out whether a given year is a leap year or
not.
if(year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
return 1;
} else {
return 0;
}
}

int main(void) {
int day, mnth, yr;
int tday, tmnth, tyr;
int i = 0;
int dayCount = 0;

//Prompt the user for birthdate.
printf("Please enter your birthday [DD/MM/YYYY]: ");

//Read in the birthday.
scanf("%2d/%2d/%4d", &day, &mnth, &yr);
printf("\n\n");

//Prompt the user for today's date.
printf("Please enter today's date [DD/MM/YYYY]: ");

//Read in the date.
scanf("%2d/%2d/%4d", &tday, &tmnth, &tyr);
printf("\n\n");

dayCount = tday; //Add this months days

// THIS BIT IS THE CODE THAT DOES NOT FUNCTION AS EXPECTED >>
// This adds all this years days up to now.
if(leapyr(tyr) != 1) {
for(i = (tmnth - 1); i > 0; i--) {
dayCount += YearDb[1][i];
}
} else {
for(i = (tmnth - 1); i > 0; i--) {
dayCount += YearDb[2][i];
}
}
// THIS BIT IS THE CODE THAT DOES NOT FUNCTION AS EXPECTED <<

// Adds all the years days from last year till the year after their
birthdate.
for(i = (tyr - 1); i > yr; i--) {
if(leapyr(i) != 1) {
dayCount += 365;
} else {
dayCount += 366;
}
}

// Adds days till the end of the month from birthday.
if(leapyr(yr) != 1) {
dayCount += (YearDb[1][mnth] - day);
} else {
dayCount += (YearDb[2][mnth] - day);
}

// Adds the remaining months of the birthyear.
if(leapyr(yr) != 1) {
for(i = (mnth + 1); i >= 12; i++) {
dayCount += YearDb[1][i];
}
} else {
for(i = (mnth + 1); i >= 12; i++) {
dayCount += YearDb[2][i];
}
}

printf("You have been alive for %d days!", dayCount);

getchar();
getchar();

return 0;
}

[ivan.coughlan]

thrhrthrt

[ivan.coughlan]

YearDb indexes are wrong - indexes start at 0 not 1. (Use the return
from the leap year function)
You should put brackets around the '||' (OR) part of 'if' in the leap
year function.
The last part ( // Adds the remaining months of the birthyear) in the
'for' statement, the expression is wrong.

[Al Bowers]

Simon Mansfield wrote:

The code has the same end result as the last one.. It must tell the user how
many days it has been since their birthday. Now it does give a result but
its normally off by a bit.. I have figured out which bit of the code is
causing this error, but, can't figure out exactly what is wrong with it! :(

..........code snipped........ ........

Instead of figuring out the errors, why don't you look at
Ray Gardner's published scalar date and time functions located at:
http://c.snippets.org/browser.php#27

Example of some of the functions provided:

#include <stdio.h>

int isleap (unsigned yr);
unsigned months_to_days (unsigned month);
long years_to_days (unsigned yr);
long ymd_to_scalar (unsigned yr, unsigned mo, unsigned day);

int main(void)
{
long today = ymd_to_scalar(2 004,12,6); /* 06DEC2004 */
long yesterday = ymd_to_scalar(2 004,12,5); /* 0DEC2004 */

printf("today - yesterday = %ld day%s\n",
today-yesterday,today-yesterday==1?"" :"s");
return 0;
}

int isleap (unsigned yr)
{
return yr % 400 == 0 || (yr % 4 == 0 && yr % 100 != 0);
}

unsigned months_to_days (unsigned month)
{
return (month * 3057 - 3007) / 100;
}

long years_to_days (unsigned yr)
{
return yr * 365L + yr / 4 - yr / 100 + yr / 400;
}

long ymd_to_scalar (unsigned yr, unsigned mo, unsigned day)
{
long scalar;
scalar = day + months_to_days( mo);
if ( mo > 2 ) /* adjust if past February */
scalar -= isleap(yr) ? 1 : 2;
yr--;
scalar += years_to_days(y r);
return scalar;
}
--
Al Bowers
Tampa, Fl USA
mailto: xa******@myrapi dsys.com (remove the x to send email)
http://www.geocities.com/abowers822/

[Simon Mansfield]

Since i've nearly got it working this way, i'd quite like to stick to this
method.. However Ivan I dont quite understand what you are saying about the
YearDb indexing.. Where have I stated that it starts at 1 in the code?

[Simon Mansfield]

Ignore my last post.. I now understand.. I was referencing [1][i] and [2][i]
when it should have been [0][i] and [1][i].. Thanks..

However I dont get what is wrong with the for statement.... Could you
clarify please?

Simon

[ivan.coughlan]

for(i = (mnth + 1); i >= 12; i++) {

1>=12 will go on forever if i starts out being greater than 12 and not
run at all if i<12.
I think you want to say '1<=12'

[ivan.coughlan]

for(i = (mnth + 1); i >= 12; i++) {

1>=12 will go on forever if i starts out being greater than 12 and not
run at all if i<12.
I think you want to say '1<=12'

[Simon Mansfield]

Ah yes, sorry being a bit blonde there for a moment! All works nicely, with
the expected result given now, so I am one happy man! ;)

Simon
<iv***********@ gmail.com> wrote in message
news:11******** **************@ f14g2000cwb.goo glegroups.com.. .

for(i = (mnth + 1); i >= 12; i++) {

1>=12 will go on forever if i starts out being greater than 12 and not
run at all if i<12.
I think you want to say '1<=12'