In any programming language, it is important to measure the execution time of our code to optimize performance and understand any potential bottlenecks. C++ provides a high-resolution clock facility through the std::chrono library, which we can leverage to measure the time taken for mathematical computations.

Including the necessary header files

First, we need to include the required header file, chrono, to utilize the std::chrono library:

#include <chrono>

Using std::chrono to measure execution time

To measure the execution time of a specific block of code, we can follow these steps:

1. Define a std::chrono::high_resolution_clock object before the code block that we want to measure:

std::chrono::high_resolution_clock::time_point startTime = std::chrono::high_resolution_clock::now();

1. Perform the mathematical computations or code that we want to measure.

2. Define another std::chrono::high_resolution_clock object after the code block:

std::chrono::high_resolution_clock::time_point endTime = std::chrono::high_resolution_clock::now();

1. Calculate the duration by subtracting the start time from the end time:

auto duration = std::chrono::duration_cast<std::chrono::microseconds>(endTime - startTime).count();

Here, we’ve used std::chrono::duration_cast to obtain the duration in microseconds. You can also choose other units such as milliseconds, seconds, etc., depending on your specific requirements.

Example usage

Let’s consider an example where we want to measure the execution time of a function that calculates the nth Fibonacci number using the recursive approach:

#include <iostream>
#include <chrono>

int fibonacci(int n) {
    if (n <= 1)
        return n;
    return fibonacci(n - 1) + fibonacci(n - 2);
}

int main() {
    int n = 30;
    
    std::chrono::high_resolution_clock::time_point startTime = std::chrono::high_resolution_clock::now();
    
    int result = fibonacci(n);
    
    std::chrono::high_resolution_clock::time_point endTime = std::chrono::high_resolution_clock::now();
    
    auto duration = std::chrono::duration_cast<std::chrono::microseconds>(endTime - startTime).count();
    
    std::cout << "Fibonacci(" << n << ") = " << result << std::endl;
    std::cout << "Execution time: " << duration << " microseconds." << std::endl;
    
    return 0;
}

In the above example, we measure the execution time of the fibonacci function by calculating the 30th Fibonacci number. The result and execution time are then printed to the console.

Conclusion

By utilizing the std::chrono library in C++, we can accurately measure the execution time of mathematical computations or any other code blocks. This allows us to optimize our programs and identify potential performance improvements.