C++ Time Measuring

• header : <ctime> or <time.h>

Usage

clock_t : Arithmetic (until C11)Real (since C11) type capable of representing the processor time used by a process. It has implementation-defined range and precision.
double cpu_time_used = ((double) (end - start))

Example

#include <algorithm>
#include <ctime>
#include <iostream>
 
int main()
{
    // Generate data
    const unsigned arraySize = 32768;
    int data[arraySize];
 
    for (unsigned c = 0; c < arraySize; ++c)
        data[c] = std::rand() % 256;
 
    // !!! With this, the next loop runs faster.
    std::sort(data, data + arraySize);
 
    // Test
    clock_t start = clock();
    long long sum = 0;
    for (unsigned i = 0; i < 100000; ++i)
    {
        for (unsigned c = 0; c < arraySize; ++c)
        {   // Primary loop
            if (data[c] >= 128)
                sum += data[c];
        }
    }
 
    double elapsedTime = static_cast<double>(clock()-start) / CLOCKS_PER_SEC;
 
    std::cout << elapsedTime << '\n';
    std::cout << "sum = " << sum << '\n';
}

C++ Cast