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unpack TEMPLATE, STRING |
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。
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) |
#!/usr/bin/perl -w
#by www.gitbook.net
$bits = pack("c", 65);
# prints A, which is ASCII 65.
print "bits are $bits\n";
$bits = pack( "x" );
# $bits is now a null chracter.
print "bits are $bits\n";
$bits = pack( "sai", 255, "T", 30 );
# creates a seven charcter string on most computers'
print "bits are $bits\n";
@array = unpack( "sai", "$bits" );
#Array now contains three elements: 255, A and 47.
print "Array $array[0]\n";
print "Array $array[1]\n";
print "Array $array[2]\n";
这将产生以下结果：
bits are A
bits are
bits are �T
Array 255
Array T
Array 30