Item 7: Never overload &&, ||, or ,

Like C, C++ employs short-circuit evaluation of boolean expressions. This means that once the truth or falsehood of an expression has been determined, evaluation of the expression ceases, even if some parts of the expression haven’t yet been examined. For example, in this case,

char *p;

...

if ((p != 0) && (strlen(p) > 10)) ...