C++ :  clock_t  clock(void) ,  CLOCKS_PER_SEC

This function returns number of clock ticks elapsed between the start of our program and current execution point.This function is declared inside <time.h>. There is also macroCLOCKS_PER_SEC which defines the number of clock ticks per second. Both are used in the following example to find out the execution time in seconds. 

#include <time.h>
ErrorCode saveContentsToDisk(string & strContentToSave)
{
 
    clock_t        start = clock();
    ....
    // the colde block we need to inspect
    ....
    clock_t       elapsedTicks = clock() - start;
    double        elapsedTimeInSeconds = elapsedTicks/CLOCK_PER_SEC
 
 
}

Windows :  GetLocalTime(), GetSystemTime()

#include <windows.h>
ErrorCode saveContentsToDisk(string & strContentToSave)
{
 
   SYSTEMTIME    startTime,endTime;
 
    GetLocalTime(&startTime);
    ....
    // the colde block we need to inspect
    ....
 
    GetLocalTime(&endTime);
 
WORD elapsedTimeInSeconds=endTime.wSecond    - startTime.wSecond;
WORD elapsedTimeInMilliSeconds = endTime.wMillisecond-startTime.wMillisecond;
 
}