很多时候
我们需要计算某段代码
操作所耗费时间我们往 往会这样写:
第
种情况精确到毫秒
clock_t start = null, end = null;
double duration = 0;
start = clock
; // operation statements here
end = clock
; duration = (double) (end - start)/CLOCK_PER_SEC;
第 2中情况
精确到秒 time_t start = null, end = null;
duration = 0; start = time(NULL);
// operation statements here
end = time(NULL);
duration = end - start;
为了是这些计时
代码能够在C
工程中重用我们可以对其进行封装 利用对象
作用域来计算时间当然这些类只能用在某些特定场合 
TimeCost {
public:
TimeCost
{ m_cur = time(NULL); ~TimeCost
{
time_t cur = time(NULL);
prinftf("Time cost is %d s\n",cur - m_cur;
}
private:
time_t m_cur;
}
TimeCost2 {
public:
TimeCost2
{ m_cur = clock;} ~TimeCost2
{
clock_t cur = clock
; double cost = (double)(cur - m_cur)/CLOCK_PER_SEC;
pr
f("Time cost: %f s \n", cost); }
private:
clock_t m_cur;
}
当然
这两个类最大缺陷就是时间计算严格依赖于对象生存期 
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