সি mktime

#include <stdio.h>
#include <time.h>

int main() {
  struct tm date = {0};

  date.tm_year = 2026 - 1900;
  date.tm_mon = 8;
  date.tm_mday = 30;

  time_t current = mktime(&date);

  printf("%lld", (long long)current);

  return 0;
}