Uninitialized pointers are known as wild pointers because they point to some arbitrary memory location and may cause a program to crash or behave unexpectedly.
Example of Wild Pointers
In the below code, p is a wild pointer.
C
// C program that demonstrated wild pointers int main()
{ /* wild pointer */
int * p;
/* Some unknown memory location is being corrupted.
This should never be done. */
*p = 12;
} |
How can we avoid wild pointers?
If a pointer points to a known variable then it’s not a wild pointer.
Example
In the below program, p is a wild pointer till this points to a.
C
int main()
{ int * p; /* wild pointer */
int a = 10;
/* p is not a wild pointer now*/
p = &a;
/* This is fine. Value of a is changed */
*p = 12;
} |
If we want a pointer to a value (or set of values) without having a variable for the value, we should explicitly allocate memory and put the value in the allocated memory.
Example
C
int main()
{ int * p = ( int *) malloc ( sizeof ( int ));
// This is fine (assuming malloc doesn't return
// NULL)
*p = 12;
} |