Question on Unions in C

So, I know that a pointer is a variable that stores a memory address (basic 4 or 8 bytes). If I place a pointer in a Union type, does the memory address stored by the pointer share the same memory space as the other types, or does the data at the memory address share the same memory?

Or, in other words, if I union a double and a char*, will I memory leak/segfault if I assign the double to anything?

>>15
It will not scale when written by a human, but it will scale if it is written by a machine that is instructed by a human.