Void Pointer (Generic Pointer)

  • In basic pointer, we have to declare integer, character and float pointer individually. But with the help of  ‘void pointer’ you have no need to declare individually which means, we can assign one pointer to all this three variable (int, char & float).
  • While dealing with the void pointer, one must & should declare typecasting (implicit) at the time of de-referencing the value.

For example :

1. main()
   {
         char ch = 'a';
         int i = 10;
         float f = 22.5;
         void *p;
         p = &ch;
         printf("%c \n", *(char *)p);  //here void pointer will work as a character pointer
         p = &i;
         printf("%d \n", *(int *)p);   //here void pointer will work as a integer pointer
         p = &f;
         printf("%f \n", *(float *)p);  //here void pointer will work as a float pointer
}
Answer: a  
        10
        22.5

 

Null Pointer:

  • A pointer holding zero as an address is called as a Null pointer.

For example :

main()
{
   int i = 10 , *p = 0; //here p = 0 means pointer has to points 0th address
   printf("%d \n", *p);  // so we get segmentation fault because this address 0th 
}                          // is not reserved for program

Use :

  • Once work with the pointer is finished, null the pointer otherwise it will affect the further program.

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