【Qt开发】Qt测试计算时间

方法1 利用QTime，其精度为ms级

</pre><pre code_snippet_id="1852215" snippet_file_name="blog_20160826_3_9895116" name="code" class="cpp">#include <QDebug>
#include <QTime>

QTime time;

time.start();
function();

qDebug()<<time.elapsed()/1000.0<<"s";

#include <QDebug>
#include <sys/time.h>

struct timeval tpstart,tpend;
float timeuse;

gettimeofday(&tpstart,NULL);
function();
gettimeofday(&tpend,NULL);
timeuse=(1000000*(tpend.tv_sec-tpstart.tv_sec) + tpend.tv_usec-tpstart.tv_usec)/1000000.0;

qDebug()<<timeuse<<"s";

#include <QDebug>
#include <sys/time.h>

double time_Start = (double)clock();
function();
double time_End = (double)clock();
    
qDebug()<<(time_End - time_Start)/1000.0<<"s";

#include <QDebug>
#include <windows.h>

LARGE_INTEGER litmp;
LONGLONG Qpart1,Qpart2,Useingtime;
double dfMinus,dfFreq,dfTime;

//获得CPU计时器的时钟频率
QueryPerformanceFrequency(&litmp);//取得高精度运行计数器的频率f,单位是每秒多少次（n/s），
dfFreq = (double)litmp.QuadPart;

QueryPerformanceCounter(&litmp);//取得高精度运行计数器的数值
Qpart1 = litmp.QuadPart; //开始计时

function(); //待测试的计算函数等

QueryPerformanceCounter(&litmp);//取得高精度运行计数器的数值
Qpart2 = litmp.QuadPart; //终止计时

dfMinus = (double)(Qpart2 - Qpart1);//计算计数器值
dfTime = dfMinus / dfFreq;//获得对应时间，单位为秒,可以乘1000000精确到微秒级（us）
Useingtime = dfTime*1000000;

qDebug()<<dfTime<<"s";