Time a function: Difference between revisions
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=={{header|C++}}==
===Using <code>ctime</code>===
<syntaxhighlight lang="cpp">#include <ctime>
#include <iostream>
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}</syntaxhighlight>
Output:
<pre>
Identity(4) takes 0 seconds.
Sum(4) takes 0.01 seconds.
</pre>
===Using <code>std::chrono</code>===
<syntaxhighlight lang="cpp">
// Compile with:
// g++ -std=c++20 -Wall -Wextra -pedantic -O0 func-time.cpp -o func-time
#include <iostream>
#include <chrono>
template<typename f>
double measure(f func) {
auto start = std::chrono::steady_clock::now(); // Starting point
(*func)(); // Run the function
auto end = std::chrono::steady_clock::now(); // End point
return std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count(); // By default, return time by milliseconds
}
/*
Test functions:
identity(): returns a number
addmillion(): add 1,000,000 to a number, one by one, using a for-loop
*/
int identity(int x) { return x; }
int addmillion(int num) {
for (int i = 0; i < 1000000; i++)
num += i;
return num;
}
int main() {
double time;
time = measure([](){ return identity(10); });
// Shove the function into a lambda function.
// Yeah, I couldn't think of any better workaround.
std::cout << "identity(10)\t\t" << time << " milliseconds / " << time / 1000 << " seconds" << std::endl; // Print it
time = measure([](){ return addmillion(1800); });
std::cout << "addmillion(1800)\t" << time << " milliseconds / " << time / 1000 << " seconds" << std::endl;
return 0;
}
</syntaxhighlight>
Output:
<pre>
identity(10) 0 milliseconds / 0 seconds
addmillion(1800) 4 milliseconds / 0.004 seconds
</pre>
=={{header|Clojure}}==
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