利用gettimeofday()，其精度为us级

TestFuncRunTime.cpp

#include <QDebug>
#include <sys/time.h>
 
struct timeval tStart;
struct timeval tEnd;
float timeUse;
 
gettimeofday(&tStart, NULL);
function();
gettimeofday(&tEnd, NULL);
 
timeUse = (1000000*(tEnd.tv_sec - tStart.tv_sec) + tEnd.tv_usec - tStart.tv_usec)/1000000.0;
 
qDebug() << timeUse << "s";