unpack

<pre name="code" class="sql">perl unpack()函数例子，unpack()函数实例代码 - 解压缩的二进制字符串STRING 使用模板TEMPLATE 中指定的格式字符串。
语法
unpack TEMPLATE, STRING


定义和用法
解压缩的二进制字符串STRING 使用模板TEMPLATE 中指定的格式字符串。基本上包反转操作，返回到所提供的格式，所述填充值的列表。

您也可以任何格式的字段的前缀％<数字>表示你想要一个16位的校验和值的字符串，而不是值。

返回值
解压后的值列表

下面是表，它给出在TEMPLATE要使用的值。

Character	Description
a	 ASCII character string padded with null characters
A	 ASCII character string padded with spaces
b	 String of bits, lowest first
B	 String of bits, highest first
c	 A signed character (range usually -128 to 127)
C	 An unsigned character (usually 8 bits)
d	 A double-precision floating-point number
f	 A single-precision floating-point number
h	 Hexadecimal string, lowest digit first
H	 Hexadecimal string, highest digit first
i	 A signed integer
I	 An unsigned integer
l	 A signed long integer
L	 An unsigned long integer
n	 A short integer in network order
N	 A long integer in network order
p	 A pointer to a string
s	 A signed short integer
S	 An unsigned short integer
u	 Convert to uuencode format
v	 A short integer in VAX (little-endian) order
V	 A long integer in VAX order
x	 A null byte
X	 Indicates "go back one byte"
@	 Fill with nulls (ASCII 0)
unpack:


unpack TEMPLATE,EXPR




TEMPLATE 要使用的值


a  ASCII 字符窜用null字符窜填充


A 用空格填充




[oracle@jhoa dbi]$ cat a4.pl 
(my $a,my $b,my $c) = unpack("a3 a5 a7", "ab:cdef:::8888ghij");
print "$a,$b,$c
";


[oracle@jhoa dbi]$ perl a4.pl 
ab:,cdef:,::8888g