The localtime function obtains the values of year, month, day, hour, minute, and second respectively.

How to Implement C language for obtaining system time in Linux:

1. You can use the localtime function to obtain the values of year, month, day, hour, minute, and second respectively.

# Include <time. h> // header file of C Language

# Include <stdio. h> // I/O of C Language

Void main ()

{

Time_t now; // instantiate the time_t Structure

Struct TM * timenow; // instantiate the TM structure pointer

Time (& now );

// The time function reads the current time (International Standard Time is not Beijing time), and then transmits the value to now

Timenow = localtime (& now );

// The localtime function converts the time now obtained from time to the time in your computer (that is, the region you set)

Printf ("local time is % s \ n", asctime (timenow ));

// In the previous sentence, the asctime function converts the time into characters and outputs the time using the printf () function.

}

Note: time_t is a struct defined in time. h. The prototype of the TM struct is as follows:

Struct TM

{

Int tm_sec; // seconds 0-61

Int tm_min; // minutes 1-59

Int tm_hour; // hours 0-23

Int tm_mday; // day of the month 1-31

Int tm_mon; // months since Jan 0-11

Int tm_year; // years from 1900

Int tm_wday; // days since Sunday, 0-6

Int tm_yday; // days since Jan 1, 0-365

Int tm_isdst; // Daylight Saving Time indicator

}; Source

2. For some requirements that require high accuracy, Linux provides gettimeofday ().

# Include <stdio. h>

# Include <stdlib. h>

# Include <sys/time. h>

Int main (INT argc, char ** argv)

{

Struct Tim start, stop, diff;

Gettimeofday (& START, 0 );

// Do what you want to do...

Gettimeofday (& stop, 0 );

Tim_subtract (& diff, & START, & stop );

Printf ("Total time: % d millisecond \ n", diff. TV _usec );

}

Int tim_subtract (struct Tim * result, struct Tim * X, struct Tim * Y)

{

Int nsec;

If (X-> TV _sec> Y-> TV _sec)

Return-1;

If (X-> TV _sec = Y-> TV _sec) & (X-> TV _usec> Y-> TV _usec ))

Return-1;

Result-> TV _sec = (Y-> TV _sec-x-> TV _sec );

Result-> TV _usec = (Y-> TV _usec-x-> TV _usec );

If (result-> TV _usec <0)

{

Result-> TV _sec --;

Result-> maid + = 1000000;

}

Return 0;

}