Date: 1998jan20 Update: 2026jul28 Language: C/C++ Q. C/C++: When is tomorrow? A. Sometimes C/C++ is so nice. Say you want to find tomorrow's date. Do you need to make a table holding the number of days in each month - and what about leap years? Nope, this fairly simple code does the trick:

#include <time.h> #include <stdio.h> void Today(int &year, int &month, int &day) { time_t now; struct tm here; now = time(NULL); // Get the current time localtime_r(&now, &here); year = here.tm_year + 1900; month = here.tm_mon + 1; day = here.tm_mday; } const time_t SECONDS_PER_DAY = 60 * 60 * 24; // Returns the date of tomorrow void Tomorrow(int &year, int &month, int &day) { time_t now; struct tm here; now = time(NULL); // Get the current time localtime_r(&now, &here); here.tm_hour = 12; // Set to noon to handle daylight savings - important here.tm_min = here.tm_sec = 0; now = mktime(&here) + SECONDS_PER_DAY; // The key line localtime_r(&now, &here); year = here.tm_year + 1900; month = here.tm_mon + 1; day = here.tm_mday; } int main() { { int year, month, day; Today(year, month, day); printf(" Today is %04d-%02d-%02d\n", year, month, day); } { int year, month, day; Tomorrow(year, month, day); printf("Tomorrow is %04d-%02d-%02d\n", year, month, day); } }

Outputs:

Today is 2026-07-28 Tomorrow is 2026-07-29