Why compiler gives error?

Question

thrust::host_vector<int> A;
thrust::host_vector<int> B;

int rand_from_0_to_100_gen(void)
{
     return rand() % 100;
}


__host__ void generateVector(int count) {


    thrust::host_vector<int> A(count);
    thrust::generate(A.begin(),A.end(),rand_from_0_to_100_gen);

    thrust::host_vector<int> B(count);
    thrust::generate(B.begin(),B.end(),rand_from_0_to_100_gen);
}

__host__ void displayVector(int count){

    void generateVector(count);

    cout << A[1];


}

In above code, why i cannot display vector values? it gives error at

void generateVector(count);

that says incomplete is not allowed Why? What's wrong here? What might be the possible solution?

Answer 1

You are calling the function generateVector incorrectly inside the function displayVector. It should be like this:

generateVector(count);

Also, you are creating vectors A and B inside the function generateVector which will be local to the function and thrust::generate will operate on these local vectors. The global vectors A and B would not be modified. You should remove the local vectors to achieve what you want. Instead call host_vector::resize for for the global vectors A and B to allocate memory.

The final code should be like this:

thrust::host_vector<int> A;
thrust::host_vector<int> B;

int rand_from_0_to_100_gen(void)
{
    return rand() % 100;
}

__host__ void generateVector(int count) 
{
    A.resize(count);
    thrust::generate(A.begin(),A.end(),rand_from_0_to_100_gen);

    B.resize(count);
    thrust::generate(B.begin(),B.end(),rand_from_0_to_100_gen);
}

__host__ void displayVector(int count)
{
    generateVector(count);
    cout << A[1]<<endl;
}