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:
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char *ListenAddresses;
...
if (ListenAddresses)
{
char *rawstring;
List *elemlist;
ListCell *l;
...
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到底何时 ListenAddress 的逻辑值为真呢?试作如下代码进行验证:
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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;
}
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编译后运行结果:ListenAddresses is NG.
再改改,运行看看:
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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;
}
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运行结果:
ListenAdresses is ok.
ListenAddresses is 192.168.2.5.
本文转自健哥的数据花园博客园博客,原文链接:http://www.cnblogs.com/gaojian/archive/2012/07/17/2595334.html,如需转载请自行联系原作者