Editing Pointer (computer programming) (section)

====Dangling pointer====
{{Main|Dangling pointer}}
A '''dangling pointer''' is a pointer that does not point to a valid object and consequently may make a program crash or behave oddly. In the [[Pascal (programming language)|Pascal]] or [[C (programming language)|C programming languages]], pointers that are not specifically initialized may point to unpredictable addresses in memory.

The following example code shows a dangling pointer:

<syntaxhighlight lang="C">
int func(void) {
    char *p1 = malloc(sizeof(char)); /* (undefined) value of some place on the heap */
    char *p2;       /* dangling (uninitialized) pointer */
    *p1 = 'a';      /* This is OK, assuming malloc() has not returned NULL. */
    *p2 = 'b';      /* This invokes undefined behavior */
}
</syntaxhighlight>

Here, <code>p2</code> may point to anywhere in memory, so performing the assignment <code>*p2 = 'b';</code> can corrupt an unknown area of memory or trigger a [[segmentation fault]].