C Library Function – difftime()

The difftime() is a C Library function that returns the difference in time, in seconds(i.e. ending time – starting time). It takes two parameters of type time_t and computes the time difference in seconds. The difftime() function is defined inside the <time.h> header file.

Syntax

The syntax of difftime() function is as follows:

double difftime(time_t time2, time_t time1);

Parameters

The difftime() function takes two parameters:

• time1: Lower bound of the time interval whose length is calculated.
• time2: Higher bound of the time interval whose length is calculated.

where time1 and time2 are variables of type time_t which is a predefined structure for calendar times.

Return Value

• Returns the difference between time1 and time2 (as measured in seconds).

Example of difftime() in C

C

// C program to demonstrate working of difftime()
#include <stdio.h>
#include <time.h>
#include <unistd.h>

// Driver Code
int main()
{
    int sec;
    time_t time1, time2;

    // Current time
    time(&time1);
    for (sec = 1; sec <= 6; sec++)
        sleep(1);

    // time after sleep in loop.
    time(&time2);
    printf("Difference is %.2f seconds",
           difftime(time2, time1));

    return 0;
}

Output

Difference is 6.00 seconds

Exception in difftime()

• It never throws an exception.