CODEWITHSUNDEEP
cpointerslocaltime
geohei
geohei

Reputation: 802

How to avoid time_t variable?

Newbie pointer/address optimization question.

As an exercise, I wrote this code.

/* -------------------------------------------------------------
FUNC    : dateplusdays (date plus days)
          add/substract days to/from date
          days can be positive or negative
PARAMS  : date (int, format yyyymmdd), days (int)
RETURNS : date (int, format yyyymmdd)
REMARKS :
---------------------------------------------------------------- */
int dateplusdays(int date_1, int days) {

    int year, month, day;
    int date_2;
    struct tm time;
    time_t time_seconds;

    year = (int) floor(date_1 / 10000.0);
    month = (int) (floor(date_1 / 100.0) - year * 100);
    day = (int) (floor(date_1) - month * 100 - year * 10000);

    time.tm_sec = 0;
    time.tm_min = 0;
    time.tm_hour = 0;
    time.tm_year = year - 1900;
    time.tm_mon = month - 1;
    time.tm_mday = day;

    time_seconds = mktime(&time) + days * 86400;
    time = *localtime(&time_seconds);

    date_2 = (time.tm_year + 1900) * 10000 + (time.tm_mon + 1) * 100 + time.tm_mday;

    return date_2;

}

Now, for exercise purpose, I'd like to put these 2 lines in one single line, hence avoiding the variable time_seconds.

    time_seconds = mktime(&time) + days * 86400;
    time = *localtime(&time_seconds);

localtime requires the address of a time_t variable. I don't see how I could skip the step using this time_t variable.

Upvotes: 3

Views: 182

Answers (1)

Secto Kia
Secto Kia

Reputation: 969

time = localtime((time_t[]){mktime(&time) + days * 86400});

This is called making a "compound literal".

Upvotes: 1

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