如何知道计算在C算法的执行时间++？ [英] How to know calculate the execution time of an algorithm in c++?

问题描述

我要测试的数据结构是最好的看着我的算法的运行时性能，我怎么办呢？

I want to test which data structure is the best by looking at the run-time performance of my algorithm, how do I do it?

例如我已经有一个的HashMap＆LT;字符串，INT＆GT; HMP ;假设我有苹果在我的的HashMap 我想知道多久下面的语句执行的时间：麝香保心丸【苹果] 。

For example I already have a hashmap<string, int> hmp; assuming I have "apple" in my hashmap I want to know how long the following statement takes to execute: hmp["apple"].

我怎样才能几点了？

谢谢！

推荐答案

首先来看看我的回答<一href="http://stackoverflow.com/questions/1861294/how-to-calculate-execution-time-of-a-$c$c-snippet-in-c/1861337#1861337">this问题;它包含了一个便携式（的Windows / Linux）函数来获得以毫秒为单位的时间。

First of all take a look at my reply to this question; it contains a portable (windows/linux) function to get the time in milliseconds.

接下来，做这样的事情：

Next, do something like this:

int64 start_time = GetTimeMs64();
const int NUM_TIMES = 100000; /* Choose this so it takes at the very least half a minute to run */

for (int i = 0; i < NUM_TIMES; ++i) {
   /* Code you want to time.. */
}

double milliseconds = (GetTimeMs64() - start_time) / (double)NUM_TIMES;

全部完成！ （请注意，我没有试图编译）

All done! (Note that I haven't tried to compile it)

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