build errors with visual studio but cuda program runs

I have been using visual studio 19 with cuda toolkit 10.1. I am able to get program examples to build and run properly. However, I always seem to have build errors that show up in visual studio. for example I get the following errors for an example that runs properly:

kernel.cu 5
Error (active) E0065 expected a ‘;’ part a example 3
kernel.cu 5
Error (active) E0169 expected a declaration part a example 3
kernel.cu 44
Error (active) E0169 expected a declaration part a example 3
kernel.cu 45

line 5
global void kernel(int* vec, int n) {

line 44-45

return 0;
}

full listing

#include <stdio.h>

#define N 10
global void kernel(int* vec, int n) {
shared int s_vec[N];
int tid = threadIdx.x;

if (tid < n)s_vec[tid] = vec[tid];
__syncthreads();

if (tid < n-1) {
int val = s_vec[tid + 1] - s_vec[tid];
vec[tid] = val;
}

}
host int main(int argc, char** argv) {
int vec_in[N] = { 6,1,7,3,2,9,10,5,4,9 };
int vec_out[N];
//char msg_in = “hello accelerator”;
//char msg_out[N];
//char* d_msg; // will be message on the device
int* d_vec;
int i;
//printf(“msg_in = %s\n”, msg_in);
cudaMalloc(&d_vec, N * sizeof(int));
//cudaMalloc(&d_msg, N * sizeof(char));

//cudaMemcpy(d_msg, msg_in, N * sizeof(char), cudaMemcpyHostToDevice);

//cudaMemcpy(msg_out, d_msg, N * sizeof(char), cudaMemcpyDeviceToHost);

//printf("msg_out= %s\n", msg_out);
cudaMemcpy(d_vec, vec_in, N * sizeof(int), cudaMemcpyHostToDevice);
kernel << <1, N >> > (d_vec, N);
cudaMemcpy(vec_out, d_vec, N * sizeof(int), cudaMemcpyDeviceToHost);
for (i = 0;i < N;++i)printf("vec_out9i)=%d\n", vec_out[i]);
//printf("vec_out[3]= %d\n", vec_out[3]);
//printf("vec_out[0]= %d\n", vec_out[0]);
//printf("vec_out[2]= %d\n", vec_out[2]);
//cudaFree(d_msg);
cudaFree(d_vec);

return 0;

}

These are intellisense errors. Intellisense is not directly compatible with CUDA. You can google around for ideas from people who have tried to work around this (for example google “cuda red underline”). Another possibility is simply to turn these types of error reporting off.

In VS2019 at the top of the build/error output window, there is a drop-down box that allows you to select display of

Build + Intellisense

Build

errors. If you change it to Build errors, you will see only errors that result from compilation.