What are Wild Pointers? How can we avoid?

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;
}