+
+Online Demo
+ +Examples
+This code can be copy and pasted in the edit box above.
+NULL pointers
+void f1(struct fred_t *p)
+{
+ // dereference p and then check if it's NULL
+ int x = p->x;
+ if (p)
+ do_something(x);
+}
+
+void f2()
+{
+ const char *p = NULL;
+ for (int i = 0; str[i] != '\0'; i++)
+ {
+ if (str[i] == ' ')
+ {
+ p = str + i;
+ break;
+ }
+ }
+
+ // p is NULL if str doesn't have a space. If str always has a
+ // a space then the condition (str[i] != '\0') would be redundant
+ return p[1];
+}
+
+void f3(int a)
+{
+ struct fred_t *p = NULL;
+ if (a == 1)
+ p = fred1;
+
+ // if a is not 1 then p is NULL
+ p->x = 0;
+}
+