异或和赋值那个速度快？

感觉异或快

异或和赋值，当然是异或快。运算比较一下就知道了。

#define NOMINMAX
#include <windows.h>
#include <stdio.h>
#include <time.h>
#include <math.h>
void accurate_dt_ms1()
{
LARGE_INTEGER nFreq;
LARGE_INTEGER nBeginTime;
LARGE_INTEGER nEndTime;
int executionTime;
int i,a=2;
double dt,d_freq,d_begin_t,d_end_t;
// Start of time interval
QueryPerformanceFrequency(&nFreq);
d_freq = (double) nFreq.QuadPart;
QueryPerformanceCounter(&nBeginTime);
// Any code
for (i=0;i<90000;i++) a=0;
// End of time interval
QueryPerformanceCounter(&nEndTime);
// time interval in ms
executionTime = (nEndTime.QuadPart - nBeginTime.QuadPart) * 1000 / nFreq.QuadPart;
dt = (double) ((nEndTime.QuadPart - nBeginTime.QuadPart) * 1000) / d_freq;
printf("==============\naccurate_dt_ms:\n");
printf("1 a=%d, dt=%d in ms or dt=%lf ms\n",a, executionTime,dt);
}
void accurate_dt_ms2()
{
LARGE_INTEGER nFreq;
LARGE_INTEGER nBeginTime;
LARGE_INTEGER nEndTime;
int executionTime;
int i,a=2;
double dt,d_freq,d_begin_t,d_end_t;
// Start of time interval
QueryPerformanceFrequency(&nFreq);
d_freq = (double) nFreq.QuadPart;
QueryPerformanceCounter(&nBeginTime);
// Any code
for (i=0;i<90000;i++) a ^=a;
// End of time interval
QueryPerformanceCounter(&nEndTime);
// time interval in ms
executionTime = (nEndTime.QuadPart - nBeginTime.QuadPart) * 1000 / nFreq.QuadPart;
dt = (double) ((nEndTime.QuadPart - nBeginTime.QuadPart) * 1000) / d_freq;
printf("==============\naccurate_dt_ms:\n");
printf("2 a=%d, dt=%d in ms or dt=%lf ms\n", a, executionTime,dt);
}
int main()
{
accurate_dt_ms1();
accurate_dt_ms2();
return 0;
}

编译器，MS VC++ 6.0
多运算几次，比较一下耗时便知。