C++ Program

Pointer arthmatic  A pointer can be implicitly converted into a bool. All non-null pointers are  equivalent to true and the null one is false. The convention is that the null  pointer correspond to a non-existing object. Static pointers are not initialized to 0 when the program starts, so  you have to be very careful when using this convention  For example, if we want to write a function that count the number of characters  into a character strings, and returns 0 if the parameter pointer is null : #include <iostream> int length(char *s) { if(s) { char *t = s; while(*t != ’\0’) t++; // The difference of two pointers is an integer return t-s;