difftime - cppreference.com (original) (raw)

Computes difference between two calendar times as time_t objects (time_end - time_beg) in seconds. If time_end refers to time point before time_beg then the result is negative.

[edit] Parameters

time_beg, time_end	-	times to compare

[edit] Return value

Difference between two times in seconds.

[edit] Notes

On POSIX systems, time_t is measured in seconds, and difftime is equivalent to arithmetic subtraction, but C and C++ allow fractional units for time_t.

[edit] Example

The following program computes the number of seconds that have passed since the beginning of the month.

#include <stdio.h> #include <time.h> int main(void) { time_t now = time(0); struct tm beg = *localtime(&now); // set beg to the beginning of the month beg.tm_hour = 0, beg.tm_min = 0, beg.tm_sec = 0, beg.tm_mday = 1; double seconds = difftime(now, mktime(&beg)); printf("%.f seconds have passed since the beginning of the month.\n", seconds); return 0; }

Output:

1937968 seconds have passed since the beginning of the month.

[edit] References