I am using boost timer in C++ builder 2009 to test the time used in my program.there are the lines:

....................

boost::timer t;

double timeresult;

...................

t.restart();

...........  //my program main body

timeresult=t.elapsed();

ShowMessage( " the time consumed by my program is "+FloatToStr(timeresult));

.........................

the program was compiled and linked and worked well.

But I find a problem:

every time the message showed is not the same time interval,

sometimes it is 0.015 and sometimes it is 0.016 and sometimes it is 0.

I do not know how it was happened.

Does it happen due to the multi-process and multi-thread mode by windows?

I do not know how to solve it. My program is quite strict on the time consumed by the computer.

Can any one with kindness help me?