Q:

header file for cuda event functions

Which header file to be included for following code snippet to measure time using cuda event mathods? 
cudaEvent_t start,stop;
cudaEventCreate(&start);
cudaEventCreate(&stop);
float Elapsed=0,Cycle;

for (int p=1; p<=MSG_NUM; p++)
{ 
    cudaEventRecord(start,0);

    add<<<R, (M+R), (M+R)* sizeof(int)>>>( d_msg, d_checkSumArray ); 

    cudaEventRecord(stop,0);
    cudaEventSynchronize(stop);
    cudaElapsedTime(&Cycle,start,stop);
    Elapsed += Cycle;
}

printf("Time = %f",Elapsed);

My program show following error as no header file included. 

error : identifier "cudaElapsedTime" is undefined

Can someone give the solution please? 

A:

The correct API call is cudaEventElapsedTime(...). 
Other than that your parameters look correct. 
You don't need any special include headers if you are compiling with nvcc.