C / C ++ time_t，以微秒为单位

Question

This program returns the time in seconds. I need to return it in microseconds .

time_t timeStart = time(0);
usleep(2.5e6);
time_t timeEnd = time(0);

float R = (timeEnd - timeStart);
std::cout << R << std::endl;

Answer 1

If you're looking for a higher resolution, you can use std::chrono::high_resolution_clock from C++11.

#include <chrono>

using namespace std::chrono;

high_resolution_clock::time_point t1 = high_resolution_clock::now();

/* some extensive action... */
usleep(2.5e6);

high_resolution_clock::time_point t2 = high_resolution_clock::now();

duration<double> time_span = duration_cast<duration<double>>(t2 - t1);

std::cout << "It took me " << time_span.count() << " seconds.";
std::cout << std::endl;

Outputs something like

It took me 0.091001 seconds.

Example from http://www.cplusplus.com/reference/chrono/high_resolution_clock/now/

Answer 2

using function gettimeofday

#include <sys/time.h>

int gettimeofday(struct timeval *tv, struct timezone *tz);
int settimeofday(const struct timeval *tv, const struct timezone *tz);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

settimeofday(): _BSD_SOURCE

Description

The functions gettimeofday() and settimeofday() can get and set the time as well as a timezone. The tv argument is a struct timeval (as specified in ):

struct timeval {
    time_t      tv_sec;     /* seconds */
    suseconds_t tv_usec;    /* microseconds */
};

and gives the number of seconds and microseconds since the Epoch (see time(2)). The tz argument is a struct timezone :

struct timezone {
    int tz_minuteswest;     /* minutes west of Greenwich */
    int tz_dsttime;         /* type of DST correction */
};

this function can get microsecond

Answer 3

Take a look at the std::chrono header. It contains many different options for time manipulation, including the ability to convert to microseconds via std::chrono::duration_cast .