Perl setprotoent 函数

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  描述

  setprotoent 应在首次调用getprotoent之前调用。STAYOPEN参数是可选的，在大多数系统上未使用。当getprotoent（）检索协议数据库中下一行的信息时，setprotoent会将枚举设置（或重置）为主机条目集的开头。
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  句法

  以下是此函数的简单语法-

  
  setprotoent STAYOPEN
  

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  返回值

  此函数不返回任何值。
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  示例

  以下是显示其基本用法的示例代码-

   
  while(($name, $aliases, $protocol_number) = getprotoent()) {
     print "Name = $name\n";
     print "Aliases = $aliases\n";
     print "Protocol Number = $protocol_number\n";
  }
  
  setprotoent(1); # Rewind the database.
  
  while(($name, $aliases, $protocol_number) = getprotoent()) {
     print "Name = $name\n";
     print "Aliases = $aliases\n";
     print "Protocol Number = $protocol_number\n";
  }
  endprotoent();  # Closes the database
  

  尝试一下

  执行以上代码后，将产生以下结果--

  
  Name = ip
  Aliases = IP
  Protocol Number = 0
  Name = hopopt
  Aliases = HOPOPT
  Protocol Number = 0
  Name = icmp
  Aliases = ICMP
  Protocol Number = 1
  Name = igmp
  Aliases = IGMP
  Protocol Number = 2
  Name = ggp
  Aliases = GGP
  Protocol Number = 3
  Name = ipencap
  Aliases = IP-ENCAP
  Protocol Number = 4
  Name = st
  Aliases = ST
  Protocol Number = 5
  Name = tcp
  Aliases = TCP
  Protocol Number = 6
  Name = egp
  Aliases = EGP
  Protocol Number = 8
  Name = igp
  Aliases = IGP
  Protocol Number = 9
  Name = pup
  Aliases = PUP
  Protocol Number = 12
  Name = udp
  Aliases = UDP
  Protocol Number = 17
  Name = hmp
  Aliases = HMP
  Protocol Number = 20
  Name = xns-idp
  Aliases = XNS-IDP
  Protocol Number = 22
  Name = rdp
  Aliases = RDP
  Protocol Number = 27
  Name = iso-tp4
  Aliases = ISO-TP4
  Protocol Number = 29
  Name = dccp
  Aliases = DCCP
  Protocol Number = 33
  Name = xtp
  Aliases = XTP
  Protocol Number = 36
  Name = ddp
  Aliases = DDP
  Protocol Number = 37
  Name = idpr-cmtp
  Aliases = IDPR-CMTP
  Protocol Number = 38
  Name = ipv6
  Aliases = IPv6
  Protocol Number = 41
  Name = ipv6-route
  Aliases = IPv6-Route
  Protocol Number = 43
  Name = ipv6-frag
  Aliases = IPv6-Frag