| Standards / Extensions | C or C++ | Dependencies |
|---|---|---|
ISO C |
both |
#include <time.h>
double difftime(time64_t time2, time_t time1);#define _LARGE_TIME_API
#include <time.h>
double difftime64(time64_t time2, time64_t time1);Computes the difference in seconds between time2 and time1, which are calendar times returned by time().
The difftime() function returns the difference between two calendar times as a double. The return value is hexadecimal floating-point or IEEE Binary Floating-Point format depending on the floating-point mode of the thread invoking difftime(). The difftime() function uses __isBFP() to determine which floating-point format (hexadecimal floating-point or IEEE Binary Floating-Point) to return on the invoking thread.
The function difftime64() will behave exactly like difftime() except it will support calendar times beyond 03:14:07 UTC on January 19, 2038 with a limit of 23:59:59 UTC on December 31, 9999.
Returns the elapsed time in seconds from time1 to time2 as a double.
⁄* CELEBD04
This example shows a timing application using &diff..
The example calculates how long, on average, it takes a
user to input some data to the program.
*⁄
#include <time.h>
#include <stdio.h>
int main(void)
{
time_t start, finish;
int i, n, num;
int answer;
printf("11 x 55 = ? Enter your answer below\n");
time(&start);
scanf("%d",&answer);
time(&finish);
printf("You answered %s in %.0f seconds.\n",
answer == 605 ? "correctly" : "incorrectly",
difftime(finish,start));
} 11 x 55 = ? Enter your answer below
605
You answered correctly in 20 seconds