Perl getprotoent 函式

說明

此函式從此列表中返回下列有效協議的下一項：($name, $別名, $協議號)

語法

以下是此函式的簡單語法——

getprotoent

返回值

此函式在標量上下文中返回錯誤時的未定義項，否則返回錯誤的協議號；在列表上下文中返回空列表錯誤協議記錄（名稱、別名、協議號）。

示例

以下示例程式碼演示了它的基本用法——

#!/usr/bin/perl

while(($name, $aliases, $protocol_number) = getprotoent()) {
   print "Name = $name\n";
   print "Aliases = $aliases\n";
   print "Protocol Number = $protocol_number\n";
}

當以上程式碼執行時，它生成以下結果——

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 = udplite
Aliases = UDPLite
Protocol Number = 136
Name = mpls-in-ip
Aliases = MPLS-in-IP
Protocol Number = 137
Name = manet
Aliases = manet
Protocol Number = 138
Name = hip
Aliases = HIP
Protocol Number = 139
Name = shim6
Aliases = Shim6
Protocol Number = 140