Question

C++

Build a struct with many data members inside (for example, a large array). Design any function that processes the data inside the struct (e.g. adding a few values together and returning the sum.) Write two versions of this function, one that passes by value and one that passes a const reference. Measure the time required to call each function 10,000 times.

Answer 1

C++ code:

#include<iostream>
#include<ctime>
using namespace std;
#define MAX 32000
struct number
{
   int arr[MAX];
};

int sum1(struct number s1)
{
   int total=0;
   for(int i=0;i<MAX;i++)
   {
       total+=s1.arr[i];
   }
   return(total);
}
int sum2(const struct number& s2)
{
   int total=0;
   for(int i=0;i<MAX;i++)
   {
       total+=s2.arr[i];
   }
   return(total);
}
int main()
{
   struct number s;
   const int CLOCKS_PER_MS=CLOCKS_PER_SEC/1000;
   for(int i=0;i<MAX;i++)
   {
       s.arr[i]=i;
   }
   clock_t start1=clock();
   for(int j=0;j<10000;j++)//call using pass by value
   {
       int sm1=sum1(s);  
   }
   clock_t end1=clock();
  
  
   clock_t start2=clock();
   for(int j=0;j<10000;j++)////call using pass by reference
   {
       int sm2=sum2(s);
   }
   clock_t end2=clock();
  
   int time1=(end1-start1)/CLOCKS_PER_MS;//calculate time for pass by value
   int time2=(end2-start2)/CLOCKS_PER_MS;//calculate time for pass by reference
  
   cout<<"Time using pass by value: "<<time1<<endl;
   cout<<"Time using pass by constant reference: "<<time2<<endl;
}

output: