unresolved external errors?

Hi everone, I am new to CUDA…

I had the 2 errors even I am just doing simple program… like this:

error LNK2019: unresolved external symbol __Znaj referenced in function _main
fatal error LNK1120: 1 unresolved externals

can anyone help me?

i have written several programs

After clearing all syntax errors from compiling,

the same 2 errors appears.

Could you post a minimal source code that produces this problem along with the command line you are using to compile it?

just a simple vector sum program:

void vector_sum_gpu( float* a, float* b, float *c);

const int width = 200;

int main(int argc, char** argv) 


	float *arrayA = new float[width];

	float *arrayB = new float[width];

	float *arrayC = new float[width];

	for(int i=0; i<width; i++ )


  arrayA[i] = i;

  arrayB[i] = i * 2;


	vector_sum_gpu(arrayA, arrayB, arrayC);

	for(int i=0; i<width; i++)

  printf("%f \n", arrayC[i]);

   CUT_EXIT(argc, argv);


void vector_sum_gpu( float* a, float* b, float *c)



   int	size;

    float *ptrA, *ptrB, *ptrC;

   size = width * sizeof(float);

    CUDA_SAFE_CALL(cudaMalloc((void**)&ptrA, size));

    CUDA_SAFE_CALL(cudaMalloc((void**)&ptrB, size));

    CUDA_SAFE_CALL(cudaMalloc((void**)&ptrC, size));

   CUDA_SAFE_CALL(cudaMemcpy(ptrA, a, size, cudaMemcpyHostToDevice));

    CUDA_SAFE_CALL(cudaMemcpy(ptrB, b, size, cudaMemcpyHostToDevice));

   VectorSum<<< 1, width >>>( ptrA, ptrB, ptrC );

   CUDA_SAFE_CALL(cudaMemcpy(c, ptrC, size, cudaMemcpyDeviceToHost));








#include <stdio.h>

__global__ void VectorSum( float* A, float* B, float* out )


    int	idx = threadIdx.x;

    out[idx] = A[idx] + B[idx];



If you are compiling two separate files, add extern “C” to the VectorSum declaration

I have added, but the errors still occur

Try to replace all “new” operators with malloc

At one point, I got similar errors (LNK2019) when my development environment

was skipping a .cu file, instead of running nvcc on it.

Check to make sure you’re running nvcc on all of your .cu files.