Struct Challange

Objective-C Programming (2nd Edition) 11. Structs
1

[code]#include <stdio.h>
/* Also, include the <time.h> header at the start of your program.*/
#include <time.h>

int main(int argc, const char * argv[])
{

/**********************Challenge***********************/
/*Your challenge is to write a program that will tell you what the date (4-30-2015 format is fine) will be in 4 million seconds*/

/*Calculate and print the number of seconds that have passed from 1970 in Greenwich England to now.*/
long secondsSince1970 = time(NULL);
printf("The time now from 1970 in Greenwich England is %ld seconds.\n", secondsSince1970);

/*Calculate and print the number of seconds four million seconds from now.*/
long fourMillionSecondsFromNow = secondsSince1970 + 4E6;
printf("Four million seconds from now is %ld seconds.\n", fourMillionSecondsFromNow);

/Use the struct tm, which is the standard C library uses to hold time broken down into its components. Reference: http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1570.pdf page 406 0f 701./
struct tm laterDate;
localtime_r(&fourMillionSecondsFromNow, &laterDate);

/*Hints: tm_mon = 0 means January, so be sure to add 1 and tm_year = 1900, so be sure to add 1900 to your year.*/
printf("The date is %d-%d-%d\n", laterDate.tm_mon+1, laterDate.tm_mday, laterDate.tm_year+1900);

return 0;

}
[/code]

2

Thanks for this. I actually missed the part where it said I needed time.h in the book. Now my program works. LOL!

3

I don’t understand what the challenge is asking of me. Structs are not confusing in theory but when on “syntax paper” it doesn’t make sense.
:neutral_face:

4

It was very tricky of whoever wrote this chapter to put the header information at the end of the challenge. :wink:

After I read this thread, it worked — here’s what I got:

[code]#include <stdio.h>
#include <time.h>

int main(int argc, const char * argv[])
{
//Today’s Seconds

long secondsSince1970 = time(NULL);
printf("It has been %ld seconds since 1970.\n", secondsSince1970);

//Today's Date

struct tm now;
localtime_r(&secondsSince1970, &now);
printf("Today's date is %d-%d-%d.\n", now.tm_mon + 1, now.tm_mday, now.tm_year + 1900);

//Future Seconds

long secondsInFourMillion = secondsSince1970 + 4000000;
printf("In four million seconds, it will have been %ld seconds since 1970.\n", secondsInFourMillion);

//Future Date

struct tm future;
localtime_r(&secondsInFourMillion, &future);
printf("The date four million seconds from now will be: %d-%d-%d.\n", future.tm_mon+1, future.tm_mday, future.tm_year + 1900);

return 0;

}[/code]