Linux 格式化结构时间规范
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Formatting struct timespec
提问by Cartesius00
How to format struct timespecto string? This structure is returned e.g. by clock_gettime()on Linux gcc:
如何格式化struct timespec为字符串？此结构由clock_gettime()Linux gcc返回，例如：
struct timespec {
time_t tv_sec; /* seconds */
long tv_nsec; /* nanoseconds */
};
采纳答案by caf
One way to format it is:
格式化它的一种方法是：
printf("%lld.%.9ld", (long long)ts.tv_sec, ts.tv_nsec)
回答by Sh4pe
You could use a std::stringstream. You can stream anything into it:
您可以使用 std::stringstream。您可以将任何内容流式传输到其中：
std::stringstream stream;
stream << 5.7;
stream << foo.bar;
std::string s = stream.str();
That should be a quite general approach. (Works only for C++, but you asked the question for this language too.)
这应该是一个非常通用的方法。（仅适用于 C++，但您也针对此语言提出了问题。）
回答by Adrian Cornish
You can pass the tv_sec parameter to some of the formatting function. Have a look at gmtime, localtime(). Then look at snprintf.
您可以将 tv_sec 参数传递给某些格式化函数。看看 gmtime, localtime()。然后看snprintf。
回答by stefanct
I wanted to ask the same question. Here is my current solution to obtain a string like this: 2013-02-07 09:24:40.749355372I am not sure if there is a more straight forward solution than this, but at least the string format is freely configurable with this approach.
我想问同样的问题。这是我当前获取这样的字符串的解决方案：2013-02-07 09:24:40.749355372我不确定是否有比这更直接的解决方案，但至少可以使用这种方法自由配置字符串格式。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#define NANO 1000000000L
// buf needs to store 30 characters
int timespec2str(char *buf, uint len, struct timespec *ts) {
int ret;
struct tm t;
tzset();
if (localtime_r(&(ts->tv_sec), &t) == NULL)
return 1;
ret = strftime(buf, len, "%F %T", &t);
if (ret == 0)
return 2;
len -= ret - 1;
ret = snprintf(&buf[strlen(buf)], len, ".%09ld", ts->tv_nsec);
if (ret >= len)
return 3;
return 0;
}
int main(int argc, char **argv) {
clockid_t clk_id = CLOCK_REALTIME;
const uint TIME_FMT = strlen("2012-12-31 12:59:59.123456789") + 1;
char timestr[TIME_FMT];
struct timespec ts, res;
clock_getres(clk_id, &res);
clock_gettime(clk_id, &ts);
if (timespec2str(timestr, sizeof(timestr), &ts) != 0) {
printf("timespec2str failed!\n");
return EXIT_FAILURE;
} else {
unsigned long resol = res.tv_sec * NANO + res.tv_nsec;
printf("CLOCK_REALTIME: res=%ld ns, time=%s\n", resol, timestr);
return EXIT_SUCCESS;
}
}
output:
输出：
gcc mwe.c -lrt
$ ./a.out
CLOCK_REALTIME: res=1 ns, time=2013-02-07 13:41:17.994326501
