time_t time( time_t  * t )

Get the current time

Returns the current timestamp as the number of seconds since January 1, 1970 (the UNIX timestamp).  The value is based on the current value of the microcontroller Real-Time Clock (RTC), which can be set using set_time.

Example

#include "mbed.h"

int main() {
    time_t seconds = time(NULL);
    printf("It is %d seconds since January 1, 1970\n", seconds);
}

Variables

void set_time( time_t  t )

Set the current time

Initialises and sets the time of the microcontroller Real-Time Clock (RTC) to the time represented by the number of seconds since January 1, 1970 (the UNIX timestamp).

Example

#include "mbed.h"

int main() {
    set_time(1256729737); // Set time to Wed, 28 Oct 2009 11:35:37
}

Variables

time_t mktime( struct  tm  * t )

Converts a tm structure in to a timestamp

Converts the tm structure in to a timestamp in seconds since January 1, 1970 (the UNIX timestamp).  The values of tm_wday and tm_yday of the tm structure are also updated to their appropriate values.

Example

#include "mbed.h"

int main() {
    // setup time structure for Wed, 28 Oct 2009 11:35:37
    struct tm t;
    t.tm_sec = 37;    // 0-59
    t.tm_min = 35;    // 0-59
    t.tm_hour = 11;   // 0-23
    t.tm_mday = 28;   // 1-31
    t.tm_mon = 9;     // 0-11
    t.tm_year = 109;  // year since 1900

    // convert to timestamp and display (1256729737)
    time_t seconds = mktime(&t);
    printf("Time as seconds since January 1, 1970 = %d\n", seconds);
}

Variables

struct tm *localtime( const  time_t  * t )

Converts a timestamp in to a tm structure

Converts the timestamp pointed to by t to a (statically allocated) tm structure.

Example

#include "mbed.h"

int main() {
    time_t seconds = 1256729737;
    struct tm *t = localtime(&seconds);
}

Variables

char *ctime( const  time_t  * t )

Converts a timestamp to a human-readable string

Converts a time_t timestamp in seconds since January 1, 1970 (the UNIX timestamp) to a human readable string format.  The result is of the format: “Wed Oct 28 11:35:37 2009\n”

Example

#include "mbed.h"

int main() {
    time_t seconds = time(NULL);
    printf("Time as a string = %s", ctime(&seconds));
}

Variables

size_t strftime( char  * buffer, size_t  max, const  char  * format, const struct  tm  * t )

Converts a tm structure to a custom format human-readable string

Creates a formated string from a tm structure, based on a string format specifier provided.

Format Specifiers

Example

#include "mbed.h"

int main() {
    time_t seconds = time(NULL);

    char buffer[32];
    strftime(buffer, 32, "%I:%M %p\n", localtime(&seconds));
    printf("Time as a formatted string = %s", buffer);
}

Variables