c - 如何获取指向结构体实例的指针成员？

Question

我有一个名为got_packet的回调函数:

void got_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet) {
  WMShark *shark = (WMShark *)args;

  WMPacket *foundPacket = [[WMPacket alloc] init];
  foundPacket.packetNumber = [[shark capturedPackets] count];

  foundPacket.timeStamp = header.ts; // <-- PROBLEM IS HERE

  ...

  NSLog(@"%@: %s", shark, packet);
}

我在 foundPacket.timeStamp = header.ts; 行上收到编译错误 错误:在非结构或 union 中请求成员“ts”。

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文档说:

...
a const struct pcap_pkthdr pointer to a structure with the following mem-bers:

• ts — a struct timeval containing the time when the packet was captured

...

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如何访问ts？谢谢。

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对于顽固的 C 开发人员来说，方括号用于 Objective-C(C 的超集)。您可以忽略这一点，在本例中它们是初始化器。

Answer 1

当您拥有指向结构的指针时，请使用 -> 运算符而不是 。:

header->ts