How Can I Accurately Measure the Execution Time of Short C Code Snippets?

Calculating Execution Time of C Code Snippets with Precision

Determining the precise execution time of code snippets in C is essential for performance analysis and optimization. However, the standard clock() function may fall short for measuring brief code segments, often returning "0 seconds."

To address this limitation, a more accurate approach is to utilize the GetTimeMs64() function, which measures elapsed time in milliseconds since the UNIX epoch, regardless of the platform (Windows or Linux).

Implementation of GetTimeMs64()

#include <ctime>
#include <chrono>

uint64_t GetTimeMs64() {
    return std::chrono::duration_cast<std::chrono::milliseconds>(
        std::chrono::system_clock::now().time_since_epoch()
    ).count();
}

GetTimeMs64() provides a high level of precision, with a granularity of 1 millisecond on most platforms.

Usage

To calculate the execution time of a code snippet, follow these steps:

uint64_t startTime = GetTimeMs64();
// Execute the code snippet
uint64_t endTime = GetTimeMs64();
double executionTime = static_cast<double>(endTime - startTime) / 1000.0;

The executionTime variable now contains the duration of the code snippet in seconds, with high precision.

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