什么是C语言怪异的用法 [英] what is the weird usage in C language

问题描述

这几天我一直在阅读了dhcpd源$ C ​​$ C，其中有许多下面这种用法重新presented，我不明白这是什么...

发生了什么事时，结构包*包; 帕拉姆列表和 {之间？

  INT locate_network（数据包）
结构包*包;
{
    结构iaddr IA;
    结构data_string数据;
    结构子网*子网=（结构子网*）0;
    结构option_cache * OC;    如果（（OC = lookup_option（安培; agent_universe，分组＆gt;选项，
               RAI_LINK_SELECT））== NULL）
    OC = lookup_option（安培; dhcp_universe，分组＆gt;选项，
               DHO_SUBNET_SELECTION）;
    // .........
}
 

解决方案

这是老K＆放大器;函数声明中的R风格，由ANSI风格，你可能更熟悉取代。另请参见函数声明：K＆安培; R VS ANSI

these days i have been reading the dhcpd source code in which there are many such usage represented below,i don't understand what that is...

what happened when the struct packet *packet; between the param list and the { ?

int locate_network (packet)
struct packet *packet;
{
    struct iaddr ia;
    struct data_string data;
    struct subnet *subnet = (struct subnet *)0;
    struct option_cache *oc;

    if ((oc = lookup_option(&agent_universe, packet->options,
               RAI_LINK_SELECT)) == NULL)
    oc = lookup_option(&dhcp_universe, packet->options,
               DHO_SUBNET_SELECTION);
    //.........
}

解决方案

That's the older K&R style of function declaration, superceded by the ANSI style you are probably more familiar with. See also Function declaration: K&R vs ANSI

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