<ctime>
struct tm * gmtime ( const time_t * timer );
Convert time_t to tm as UTC time
Uses the value pointed by timer to fill a tm structure with the values that represent the corresponding time, expressed as UTC (or GMT timezone).
Parameters
- timer
- Pointer to a time_t value representing a calendar time (see time_t).
Return Value
A pointer to a tm structure with the time information filled in.
This structure is statically allocated and shared by the functions gmtime and localtime. Each time either one of these functions is called the contents of this structure is overwritten.
Example
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/* gmtime example */
#include <stdio.h>
#include <time.h>
#define MST (-7)
#define UTC (0)
#define CCT (+8)
int main ()
{
time_t rawtime;
tm * ptm;
time ( &rawtime );
ptm = gmtime ( &rawtime );
puts ("Current time around the World:");
printf ("Phoenix, AZ (U.S.) : %2d:%02d\n", (ptm->tm_hour+MST)%24, ptm->tm_min);
printf ("Reykjavik (Iceland) : %2d:%02d\n", (ptm->tm_hour+UTC)%24, ptm->tm_min);
printf ("Beijing (China) : %2d:%02d\n", (ptm->tm_hour+CCT)%24, ptm->tm_min);
return 0;
}
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Output:
Current time around the World:
Phoenix, AZ (U.S.) : 8:26
Reykjavik (Iceland) : 15:26
Beijing (China) : 23:26
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See also
| asctime | Convert tm structure to string (function) |
| ctime | Convert time_t value to string (function) |
| localtime | Convert time_t to tm as local time (function) |
| mktime | Convert tm structure to time_t (function) |
| time | Get current time (function) |
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