添加兩個數字CUDA

Question

我正在學習CUDA並需要一些幫助。 這是我的計劃，從NVIDIA的介紹：

__global__ void add(int *a, int *b, int *c) 
    { 
     *c = *a + *b; 
    } 

    int main(void) { 
     int a, b, c; // host copies of a, b, c 
     int *d_a, *d_b, *d_c; // device copies of a, b, c 
     int size = sizeof(int); 

     // Allocate space for device copies of a, b, c 
     cudaMalloc((void **)&d_a, size); 
     cudaMalloc((void **)&d_b, size); 
     cudaMalloc((void **)&d_c, size); 

     // Setup input values 
     a = 2; 
     b = 7; 

     // © NVIDIA Corporation 2011 
     // Addition on the Device: main() 
     // Copy inputs to device 
     cudaMemcpy(d_a, &a, size, cudaMemcpyHostToDevice); 
     cudaMemcpy(d_b, &b, size, cudaMemcpyHostToDevice); 

     // Launch add() kernel on GPU 
     add<<<1,1>>>(d_a, d_b, d_c); 

     // Copy result back to host 
     cudaMemcpy(&c, d_c, size, cudaMemcpyDeviceToHost); 

     // Cleanup 
     cudaFree(d_a); cudaFree(d_b); cudaFree(d_c); 

     printf("%d",&c); 
     return 0; 
    } 

每次我運行此代碼的c值不是9 如何獲得的c真正的價值？

Answer 1

嘗試

printf("%d", c); 

，而不是

printf("%d", &c); 

你目前正在打印的局部變量c，而不是它的價值