c - When is it necessary to allocate dynamic memory using malloc on pointers? -

I'm having difficulty understanding the malloc () function in C, more accurately when using it

When I declare a global structure like this indicator,

  struct position * currentPositionPtr;   
 Do I need to use dynamic malloc to start using malloc? Or is it a good practice to allocate it to an indicator of the structure later, such as when it is necessary  
  current PositionPtr = getPosition ();   
 Where  getPosition ()  returns an indicator on "indicator status".   
 
 
 What does  getPosition () ?  
 If it returns a valid indicator for the  struct state , then surely you do not need to assign memory to  twice the  structure. I hope your  no  look like this:  
  struct status * getPosition () {struct position p = {x, y}; Return and p; }   
 Because it will display undefined behavior (by returning a pointer to a block scope automated object) Generally, you instead of  already   malloc ()  Returns the pointer on the screen:  
  struct position * getPosition () {struct position * p = malloc (sizeof (* P)); P-> x = 42; P-> Y = 1337; Return p; }   
 Then, then you do not need to call  additional  at  malloc () .  
 If, however, this is not a function to be said which is responsible for allocation, then, well ... it is a collar:  
  zero getPosition ( Struct position * p) {p-> gt; X = 42; P-> Y = 1337; }   
 And in the latter case you have to call it this way:  
  struct position * p = malloc (sizeof (* p)) ; GetPosition (P);   
 If the function returns you need your structure to survive, or  
  struct position p; GetPosition (& amp; P);   
 If you do not.