linux 如何计算程序运行时间

time ./your_program

real    0m0.002s
user    0m0.001s
sys     0m0.001s

start=$(date +%s%N)
./your_program
end=$(date +%s%N)
elapsed=$(( (end - start) / 1000000 ))
echo "Elapsed time: $elapsed ms"

#include <iostream>
#include <ctime>

int main() {
    clock_t start = clock();
    // ... your program code ...
    clock_t end = clock();
    double elapsed_secs = double(end - start) / CLOCKS_PER_SEC;
    std::cout << "Elapsed time: " << elapsed_secs << "s\n";
    return 0;
}

#include <iostream>
#include <chrono>

int main() {
    auto start = std::chrono::high_resolution_clock::now();
    // ... your program code ...
    auto end = std::chrono::high_resolution_clock::now();
    std::chrono::duration<double> elapsed = end - start;
    std::cout << "Elapsed time: " << elapsed.count() << "s\n";
    return 0;
}