对函数输入变量的指针赋值但是为空


I’m using it here to assign a value to the CurrentNode pointer

I’m calling it in this picture’s function, and I’m calling it with a SelectedNode

This SelectedNode is right here, and I’m calling this function where this pointer should be able to be assigned directly, but why, with the way I did it in the first picture, this SelectedNode function is going to be empty after this function, and the only way it’s not going to be empty is to assign the pointer directly to the SelectedNode.
I don’t understand why