Vector additon cuda program

vectorAddition.cu

#include<iostream>
#include<cstdlib>

using namespace std;

//VectorAdd parallel function
__global__ void vectorAdd(int *a, int *b, int *result, int n)
{
    int tid=threadIdx.x+blockIdx.x*blockDim.x;
    if(tid<n)
    {
        result[tid]=a[tid]+b[tid];
    }
}
int main()
{
    int *a,*b,*c;
    int *a_dev,*b_dev,*c_dev;
    int n=1<<24;
    
    a=new int[n];
    b=new int[n];
    c=new int[n];
    int *d=new int[n];
    int size=n*sizeof(int);
    cudaMalloc(&a_dev,size);
    cudaMalloc(&b_dev,size);
    cudaMalloc(&c_dev,size);
    
    //Array initialization..You can use Randon function to assign values
    for(int i=0;i<n;i++)
    {
        a[i]=1;
        b[i]=2;
        d[i]=a[i]+b[i]; //calculating serial addition
    }
    
    
    cudaEvent_t start,end;
    
    cudaEventCreate(&start);
    cudaEventCreate(&end);
    
    cudaMemcpy(a_dev,a,size,cudaMemcpyHostToDevice);
    cudaMemcpy(b_dev,b,size,cudaMemcpyHostToDevice);
    int threads=1024;
    int blocks=(n+threads-1)/threads;
    cudaEventRecord(start);
    
    //Parallel addition program
    vectorAdd<<<blocks,threads>>>(a_dev,b_dev,c_dev,n);
    
    cudaEventRecord(end);
    cudaEventSynchronize(end);
    
    float time=0.0;
    cudaEventElapsedTime(&time,start,end);
    
    cudaMemcpy(c,c_dev,size,cudaMemcpyDeviceToHost);
    
    //Calculate the error term.
    int error=0;
    for(int i=0;i<n;i++){
        error+=d[i]-c[i];
        //cout<<" gpu "<<c[i]<<" CPU "<<d[i];
    }
    
    cout<<"Error : "<<error;
    cout<<"\nTime Elapsed:  "<<time;
    
    return 0;
}