do{} while(0)好處
替代{},實現區域性作用域.
#define fun()
do { fun1(); fun2(); } while(0)
if (condition) fun(); else { ... }; // ok
// compared with
#define fun() {fun1(); fun2(); }
if (condition) fun(); else { ... }; // compile error; 避免使用goto,用break做跳出.
do {
fun1();
...
fun2();
if (condition) {
break;
}
fun3();
fun4();
} while(0);