postmaster.c 中的 ListenAddresses
在 postmaster.c 中看到这种代码,从Java程序员的角度,看起来是很不爽的:
char *ListenAddresses; ... if (ListenAddresses) { char *rawstring; List *elemlist; ListCell *l; ...
到底何时 ListenAddress 的逻辑值为真呢?试作如下代码进行验证:
char *ListenAddresses; int main(int argc, char **argv) { if (ListenAddresses){ fprintf(stderr, "ListenAddresses is ok.\n"); }else{ fprintf(stderr, "ListenAddresses is NG.\n"); } return 0; }
编译后运行结果:ListenAddresses is NG.
再改改,运行看看:
char *ListenAddresses; int main(int argc, char **argv) { ListenAddress="192.168.2.5"; if (ListenAddress){ fprintf(stderr, "ListenAddresses is ok.\n"); fprintf(stderr, "ListenAddresses is %s.\n",ListenAddress); }else{ fprintf(stderr, "ListenAddresses is NG.\n"); } return 0; }
运行结果:
ListenAdresses is ok.
ListenAddresses is 192.168.2.5.