All CUDA API functions return an error code (or cudaSuccess if no error occured). All other parameters are passed by reference. However, in plain C you cannot have references, that's why you have to pass an address of the variable that you want the return information to be stored. Since you are returning a pointer, you need to pass a double-pointer.

简单来说 C里面，当cudamalloc被调用时，将创建一个名为d_array的局部变量，并为其分配第一个函数参数的值。这个是无法在函数范围之外检索该局部变量中的值的。所以说要用双指针。

二级指针一律按指针数组处理

这个和c语言的一些特性也有关系，c和c++引用和函数重构都不太一样，我记得c++不用double pointer。

快

这回不葱了，改chonglangoverflow了是吧