Date calculation program

This is a discussion on Date calculation program within the C Programming forums, part of the General Programming Boards category; Hi there, The programe below outputs the difference between two dates, i want to edit it so the 1st date ...

  1. #1
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    Date calculation program

    Hi there,

    The programe below outputs the difference between two dates, i want to edit it so the 1st date is always today's date. Would i need to use the time function or rawtime. I am struggling to integrate it into the format of this programme. Could anyone point me in the right direction?

    Code:
    #include <stdio.h> //
    
    #include <time.h> // Include C time functions in header
    
    int daysto(struct tm *before, struct tm *after) // Grouping code for daysto calculation
    
    {
    
    time_t first = mktime(before), second = mktime(after); // Declaring time_t
    
    if ( first != (time_t)-1 && second != (time_t)-1 ) // If first and second date is not equal return the difference
    
    {
    
    return difftime(second, first) / (60 * 60 * 24); // Converting time into days. difftime function for first and second date
    
    }
    
    return-1 ; //Anything non zero is true
    
    }
    
    int main(void) // Function takes no arguements
    
    {
    
    struct tm one = {0}, two = {0}; 
    
     
    
    one.tm_year = 109; // mktime function caclculates from the year 1900 
    
    one.tm_mon = 3 - 1; // Month input. Months start a 0 so -1 
    
    one.tm_mday = 24; // Day of the month input 
    
    
    two.tm_year = 109; // mktime function calculates from the year 1900 
    
    two.tm_mon = 4 - 1; // Month input. Months start a 0 so -1 
    
    two.tm_mday = 3; // Day of the month input 
    
    printf("Number of days till deadline = %d\n", daysto(&one,&two)); // Printing the result of the calculation 
    
    return 0;
    
    }

    Thanks in advance

  2. #2
    Kernel hacker
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    The function time() will give you current time() in the same format as mktime() gives you.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  3. #3
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    Sorry to bring this up again so long after I posted, but i am still struggling with this problem. I have tried to include time() into the code, but I'm not sure how I should edit this part of the code:

    Code:
     
    
    one.tm_year = 109; // mktime function caclculates from the year 1900 
    
    one.tm_mon = 3 - 1; // Month input. Months start a 0 so -1 
    
    one.tm_mday = 24; // Day of the month input
    This is the bit which i want to always be todays date. Would i just leave each one as 'one.tm_mon' or do i need some kind of variable for each part?

    Sorry if this is a stupid question, just can't get my head around it!

  4. #4
    Kernel hacker
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    Code:
      time_t t;
      struct tm one;
    
      time(&t);
    
      one = *localtime(&t);
    
       // If needed, set hours, minutes and seconds to zero.
    Sorry all, I'm giving away fish here

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  5. #5
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    ahh it works! thank you

  6. #6
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    You do what you gotta do, Mats.

    It's great watching you land 'em!

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