{"post":"

Wild and Double Pointer :

Wild Pointers:

If a pointer is not initialised to anything, not even NULL, is called a Wild Pointer. The pointer is assigned to a garbage value which may not even be a valid address. Such pointers point to some arbitrary memory location.
\nLet us look at the code snippet below to understand wild pointers:

    int  main() {\r\n       int  * ptr;  // ptr is a wild pointer\r\n       int  num = 10;\r\n       p = & x; //ptr is not a wild pointer anymore\r\n       return  0;\r\n    }\r\n

ptr is an int type pointer. Since it has not been initialized to anything, not even NULL, it is a wild pointer.
When ptr is made to point to num, it stores the address of num. Since now ptr is pointing to a valid memory address, it is not a wild pointer anymore.

Double Pointers:

A pointer to a pointer is called a double pointer.
\nLets say we have two pointers and a normal variable.
\nThe first pointer stores the address of a variable. The second pointer, which is the double pointer, stores the address of the first pointer. A double pointer is also known as pointer-to-pointer.
\nDeclaring a double pointer is similar to declaring a pointer.
\nSyntax:

type **pointerName\r\n

typespecifies the type of the pointer. It must a valid type in C.
** indicate that the pointer is a double pointer.
pointerNameis the name of the pointer variable.

Let us look at a code snippet to understand double pointers:

#include<stdio.h>\r\n     \r\n    int main()\r\n    {\r\n        int num = 10; //normal variable\r\n         \r\n         \r\n        int *ptr1; // pointer for num\r\n         \r\n        int **ptr2; // double pointer for ptr1\r\n         \r\n        ptr1 = # // assigning address of num in ptr1\r\n                \r\n               ptr2 = &ptr1; // assigning address of ptr1 in ptr2\r\n         \r\n        printf(\"Value of num = %d\\n\", num );\r\n        printf(\"Value of num using single pointer = %d\\n\", *ptr1 );\r\n        printf(\"Value of num using double pointer = %d\\n\", **ptr2);\r\n    }\r\n

We have created an int type variable numthat stores value 10
We have created a pointer ptr1to point to num
We have created a pointer ptr2 to point to ptr1
ptr1 stores the address of numand ptr2 stores the address of ptr1

The above code snippet gives the following output:

Value of num = 10\r\nValue of num using single pointer = 10\r\nValue of num using double pointer = 10\r\n

The diagram is a pictorial representation of the above code.
\n $\"\"$
\nSome important statements to remember concerning single and double pointers:

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n

Statement	Output
*ptr1	10
**ptr2	10
ptr1	&num (i.e. address of num)
ptr2	&ptr1 (i.e. address of ptr)

\n","title":"Wild Pointer in C | Double Pointers in C","authorDetails":{"name":"Namrata Jangid","slug":"namrata-jangid"},"seo":{"title":"Wild Pointer in C | Double Pointers in C"},"description":"If a pointer is not initialised to anything, not even NULL, is called a Wild Pointer. Learn more about wild and double pointer in C programming language...","slug":"blog/wild-and-double-pointer-in-c","articleId":"636a834b7bb1ce5072622cbe","bookmarkStatus":{"isBookmarked":false,"bookmarkId":null}}