realloc structure with function in C

Question

My C program is crashing and I am too new to figure it out. It\'s very simple so far and I imagine the code is enough to figure out what is going wrong.

I am simply try

Answer 1

Combining Ingo's and codroipo's answers, you have to either return the new pointer from double_array_size, or you have to pass in a pointer to d so you can update the pointer from double_array_size