如何將void *轉換爲float（*）[3]在C++中？

Question

這是代碼片段。

typedef struct Lib3dsMesh { 
//.. 
float (*vertices)[3]; 
//.. 
} 


void* lib3ds_util_realloc_array(void *ptr, int old_size, int new_size, int element_size) { 
    // Do something here. 
    return ptr; 
} 


mesh->vertices = lib3ds_util_realloc_array(mesh->vertices, mesh->nvertices, nvertices, 3 * sizeof(float)); 

當我在visual C++中編譯此代碼時，它返回錯誤「無法從void *轉換爲float（*）[3]」。我想知道如何投射void * float（* vertices）[3];

Answer 1

vertices是pointer to a 3-element array of float。要做到從一個指針類型到另一種轉換，你通常使用static_cast：

void* result = lib3ds_util_realloc_array(
    mesh->vertices, mesh->nvertices, nvertices, 3 * sizeof(float)); 
mesh-vertices = static_cast<float (*)[3]>(result);