为什么CLOCKS_PER_SEC不是每秒钟的实际时钟数？

问题描述

  #include< p>我已经写了这个简短的C ++程序来估计每秒的实际时钟节拍数。 iostream> 
 #include< time.h> 
 
 using namespace std; 
 
 int main（）{
 
 for（int i = 0; i  
 int first_clock = clock ; 
 int first_time = time（NULL）; 
 
 while（time（NULL）< = first_time）{} 
 
 int second_time = time（NULL）; 
 int second_clock = clock（）; 
 
 cout<< 实际时钟每秒=< （second_clock  -  first_clock）/（second_time-first_time）< \\\
; 
 
 cout<< CLOCKS_PER_SEC =< CLOCKS_PER_SEC<< \\\
; 
 
} 
 
 return 0; 
 
} 
  

当我运行程序时，

 每秒实际时钟数= 199139 
 CLOCKS_PER_SEC = 1000000 
每秒实际时钟数= 638164 
 CLOCKS_PER_SEC = 1000000 
每秒实际时钟数= 610735 
 CLOCKS_PER_SEC = 1000000 
每秒实际时钟数= 614835 
 CLOCKS_PER_SEC = 1000000 
每秒实际时钟数= 642327 
 CLOCKS_PER_SEC = 1000000 
每秒实际时钟数= 562068 
 CLOCKS_PER_SEC = 1000000 
每秒实际时钟数= 605767 
 CLOCKS_PER_SEC = 1000000 
每秒实际时钟数= 619543 
 CLOCKS_PER_SEC = 1000000 
每秒实际时钟数= 650243 
 CLOCKS_PER_SEC = 1000000 
每秒实际时钟数= 639128 
 CLOCKS_PER_SEC = 1000000 
  

为什么CLOCKS_PER_SEC每秒钟的实际时钟滴答数不匹配？他们甚至不相等。这是怎么回事？

解决方案

clock 返回花费的时间 每秒总共有1,000,000个时钟滴答。。您的程序似乎占用了其中的60％。

其他40％的用途。

sup> *

I have just written this short C++ program to approximate the actual number of clock ticks per second.

#include <iostream>
#include <time.h>

using namespace std;

int main () {

    for(int i = 0; i < 10 ; i++) {

        int first_clock = clock();
        int first_time = time(NULL);

        while(time(NULL) <= first_time) {}

        int second_time = time(NULL);
        int second_clock = clock();

        cout << "Actual clocks per second = " << (second_clock - first_clock)/(second_time - first_time) << "\n";

        cout << "CLOCKS_PER_SEC = " << CLOCKS_PER_SEC << "\n";

    }

    return 0;

}

When I run the program, I get output that looks like this.

Actual clocks per second = 199139
CLOCKS_PER_SEC = 1000000
Actual clocks per second = 638164
CLOCKS_PER_SEC = 1000000
Actual clocks per second = 610735
CLOCKS_PER_SEC = 1000000
Actual clocks per second = 614835
CLOCKS_PER_SEC = 1000000
Actual clocks per second = 642327
CLOCKS_PER_SEC = 1000000
Actual clocks per second = 562068
CLOCKS_PER_SEC = 1000000
Actual clocks per second = 605767
CLOCKS_PER_SEC = 1000000
Actual clocks per second = 619543
CLOCKS_PER_SEC = 1000000
Actual clocks per second = 650243
CLOCKS_PER_SEC = 1000000
Actual clocks per second = 639128
CLOCKS_PER_SEC = 1000000

Why doesn't the actual number of clock ticks per second match up with CLOCKS_PER_SEC? They're not even approximately equal. What's going on here?

解决方案

clock returns the amount of time spent in your program. There are 1,000,000 clock ticks per second total. It appears that your program consumed 60% of them.

Something else used the other 40%.

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