关于获取当前UTC时间与某一时间的时间差问题
假如我现在获取到当前utc时间，如何得到它与今晚12点时间的差值？
求方法
[解决办法]
再获得今晚12点的utc时间，然后相减。
[解决办法]
struct tm ，time_t互相转换就可以了，具体使用参看msdn或百度
[解决办法]
difftime
Finds the difference between two times.
double difftime( time_t timer1, time_t timer0 );
Routine Required Header Compatibility
difftime <time.h> ANSI, Win 95, Win NT
For additional compatibility information, see Compatibility in the Introduction.
Libraries
LIBC.LIB Single thread static library, retail version
LIBCMT.LIB Multithread static library, retail version
MSVCRT.LIB Import library for MSVCRT.DLL, retail version
Return Value
difftime returns the elapsed time in seconds, from timer0 to timer1. The value returned is a double-precision floating-point number.
Parameters
timer1
Ending time
timer0
Beginning time
Remarks
The difftime function computes the difference between the two supplied time values timer0 and timer1.
Example
/* DIFFTIME.C: This program calculates the amount of time
* needed to do a floating-point multiply 10 million times.
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
void main( void )
{
time_t start, finish;
long loop;
double result, elapsed_time;
printf( "Multiplying 2 floating point numbers 10 million times...\n" );
time( &start );
for( loop = 0; loop < 10000000; loop++ )
result = 3.63 * 5.27;
time( &finish );
elapsed_time = difftime( finish, start );
printf( "\nProgram takes %6.0f seconds.\n", elapsed_time );
}
Output
Multiplying 2 floats 10 million times...
Program takes 2 seconds.
Floating-Point Support Routines | Time Management Routines
See Also time
[解决办法]
COleDateTime
COleDateTimeSpan
