C语言库函数的原型,有用的拿去

				/***
				*clock.c - Contains the clock runtime
				*
				*       Copyright (c) Microsoft Corporation. All rights reserved.
				*
				*Purpose:
				*       The clock routine calculates the amount of elapsed time
				*       since the current process was started.
				*
				*******************************************************************************/
				
				#include 
				#include 
				#include 
				#include 
				#include 
				
				#include 
				#include 
				#include 
				
				
				
				int __cdecl __inittime(void);
				
				_CRTALLOC(".CRT$XIC") static _PIFV pinit = __inittime;
				
				static unsigned __int64 start_tics;
				
				/***
				*clock_t clock() - Return the processor time used by this process.
				*
				*Purpose:
				*       This routine calculates the amount of elapsed time
				*       since the current process was started.
				*       At startup time, startup calls __inittime which stores
				*       the initial time.  The clock routine calculates the difference
				*       between the current time and the initial time.
				*
				*       Clock must reference _cinitime so that _cinitim.asm gets linked in.
				*       That routine, in turn, puts __inittime in the startup initialization
				*       routine table.
				*
				*Entry:
				*       No parameters.
				*       itime is a static structure of type timeb.
				*
				*Exit:
				*       If successful, clock returns the number of CLK_TCKs (milliseconds)
				*       that have elapsed.  If unsuccessful, clock returns -1.
				*
				*Exceptions:
				*       None.
				*
				*******************************************************************************/
				
				clock_t __cdecl clock (
				        void
				        )
				{
				        unsigned __int64 current_tics;
				        FILETIME ct;
				
				        GetSystemTimeAsFileTime( &ct );
				
				        current_tics = (unsigned __int64)ct.dwLowDateTime +
				                       (((unsigned __int64)ct.dwHighDateTime) 				
				        /* calculate the elapsed number of 100 nanosecond units */
				        current_tics -= start_tics;
				
				        /* return number of elapsed milliseconds */
				        return (clock_t)(current_tics / 10000);
				}
				
				/***
				*int __inittime() - Initialize the time location
				*
				*Purpose:
				*       This routine stores the time of the process startup.
				*       It is only linked in if the user issues a clock runtime call.
				*
				*Entry:
				*       No arguments.
				*
				*Exit:
				*       Returns 0 to indicate no error.
				*
				*Exceptions:
				*       None.
				*
				*******************************************************************************/
				
				int __cdecl __inittime (
				        void
				        )
				{
				        FILETIME st;
				
				        GetSystemTimeAsFileTime( &st );
				
				        start_tics = (unsigned __int64)st.dwLowDateTime +
				                     (((unsigned __int64)st.dwHighDateTime) 				
				        return 0;
				}